Liver fibrosis

JunD is a profibrogenic transcription factor regulated by Jun N-terminal kinase-independent phosphorylation

JunD is implicated in the regulation of hepatic stellate cell (HSC) activation and liver fibrosis via its transcriptional regulation of the tissue inhibitor of metalloproteinases-1 (TIMP-1) gene. In the present study we found in vivo evidence of a role for JunD in fibrogenesis. Expression of JunD was demonstrated in alpha-SMA-positive activated HSCs of fibrotic rodents and human livers. The junD-/- mice were protected from carbon tetrachloride-induced fibrosis. The livers of injured junD-/- mice displayed significantly reduced formation of fibrotic crosslinked collagen and a smaller number of alpha-SMA-positive HSCs compared with those of wild-type (wt) mice. Hepatic TIMP-1 mRNA expression in injured junD-/- mice was 78% lower and in culture activated junD-/- HSCs was 50%-80% lower than that in wt mice. In examining the signal transduction mechanisms that regulate JunD-dependent TIMP-1 expression, we found a role for phosphorylation of the Ser100 residue of JunD but ruled out JNK as a mediator of this event, suggesting ERK1/2 is utilized. In conclusion, a signaling pathway for the development of fibrosis involves the regulation of TIMP-1 expression by phosphorylated JunD.

Changes of the hepatic proteome in murine models for toxically induced fibrogenesis and sclerosing cholangitis

We investigated the changes in the hepatic proteome in murine models for toxic-induced fibrogenesis and sclerosing cholangitis. A comprehensive comparison of protein changes observed is made and the mechanistical basis of the expression changes is discussed. Hepatic fibrosis was induced by repetitive intraperitoneal CCl4 treatment of BALB/c mice or developed spontaneously in BALB/c-ATP-binding cassette, subfamily B, member 4 (Abcb4) knock out mice. Fibrosis was verified by a morphometric score and assessment of hydroxyproline content of liver tissue, respectively. The innovative difference in-gel electrophoresis (DIGE) technique was used to analyse protein expression levels of the mouse proteome. Results were confirmed by Western blotting and real-time RT-PCR. In CCl4-induced fibrosis 20 out of 40 and in BALB/c-Abcb4(-/-) mice 8 out of 28 differentially expressed proteins were identified utilizing DIGE. Only two proteins, selenium-binding protein (Sbp2) and carbonic anhydrase 3, have been unidirectionally expressed (i.e. down-regulated) in both models. Relevant differences in the pathogenesis of toxically induced liver fibrosis and sclerosing cholangitis exist. The only novel protein with regard to liver fibrosis depicting a unidirectional expression pattern in both animal models was Sbp2. An explicit protein function could not be clarified yet.

Hepatitis B virus promotes angiopoietin-2 expression in liver tissue: role of HBV x protein

The progression of chronic hepatitis B (CHB) is related to fibrosis and to the emergence of intrahepatic anomalous vascular structures. Hepatitis B virus (HBV) X protein transactivator (HBx) may play a significant role in both processes. To analyze how HBV induces vascular growth and remodeling in vivo, we assessed the expression of angiopoietin-2 (Ang2) in liver biopsies from CHB patients by reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry because of the relevant role of Ang2 in vascular development, remodeling, and tumor promotion. In addition, we analyzed the influence of HBx in the expression of Ang2 in HBx-expressing hepatocyte cell lines and in hepatic stellate cells stimulated with conditional medium from HBx-hepatocytes. Ang2 expression was clearly up-regulated at both mRNA and protein levels in the liver of CHB patients, showing an intense staining of inflammatory infiltrates and vascular structures at inflamed portal areas. HBx-expressing hepatocytes and stimulated stellate cells showed a significant induction of Ang2 expression. PI3K inhibitor and antioxidants repressed the 64-kd Ang2 form but further enhanced the inflammation-related 50-kd molecular species. Therefore, HBx could account for the induction of Ang2 observed in CHB, especially the 50-kd form, contributing to pathological angiogenesis and hepatocellular carcinoma progression.

Morphological characterisation of portal myofibroblasts and hepatic stellate cells in the normal dog liver

Background

Hepatic fibrosis is a common outcome of hepatic injury in both man and dog. Activated fibroblasts which develop myofibroblastic characteristics play an essential role in hepatic fibrogenesis, and are comprised of three subpopulations: 1) portal or septal myofibroblasts, 2) interface myofibroblasts and 3) the perisinusoidally located hepatic stellate cells (HSC). The present study was performed to investigate the immunohistochemical characteristics of canine portal myofibroblasts (MF) and HSC in the normal unaffected liver as a basis for further studies on fibrogenesis in canine liver disease.

Results

In the formalin-fixed and paraffin embedded normal canine liver vimentin showed staining of hepatic fibroblasts, probably including MF in portal areas and around hepatic veins; however, HSC were in general negative. Desmin proved to react with both portal MF and HSC. A unique feature of these HSC was the positive immunostaining for alpha-smooth muscle actin (α-SMA) and muscle-specific actin clone HHF35 (HHF35), also portal MF stained positive with these antibodies. Synaptophysin and glial fibrillary acidic protein (GFAP) were consistently negative in the normal canine liver. In a frozen chronic hepatitis case (with expected activated hepatic MF and HSC), HSC were negative to synaptophysin, GFAP and NCAM. Transmission electron microscopy (TEM) immunogold labelling for α-SMA and HHF35 recognized the positive cells as HSC situated in the space of Disse.

Conclusion

In the normal formalin-fixed and paraffin embedded canine liver hepatic portal MF and HSC can be identified by α-SMA, HHF35 and to a lesser extent desmin immunostaining. These antibodies can thus be used in further studies on hepatic fibrosis. Synaptophysin, GFAP and NCAM do not seem suitable for marking of canine HSC. The positivity of HSC for α-SMA and HHF35 in the normal canine liver may eventually reflect a more active regulation of hepatic sinusoidal flow by these HSC compared to other species.

CARMA3/Bcl10/MALT1-dependent NF-kappaB activation mediates angiotensin II-responsive inflammatory signaling in nonimmune cells

Angiotensin II (Ang II) is a peptide hormone that, like many cytokines, acts as a proinflammatory agent and growth factor. After injury to the liver, the hormone assists in tissue repair by stimulating hepatocytes and hepatic stellate cells to synthesize extracellular matrix proteins and secrete secondary cytokines and by stimulating myofibroblasts to proliferate. However, under conditions of chronic liver injury, all of these effects conspire to promote pathologic liver fibrosis. Much of this effect of Ang II results from activation of the proinflammatory NF-kappaB transcription factor in response to stimulation of the type 1 Ang II receptor, a G protein-coupled receptor. Here, we characterize a previously undescribed signaling pathway mediating Ang II-dependent activation of NF-kappaB, which is composed of three principal proteins, CARMA3, Bcl10, and MALT1. Blocking the function of any of these proteins, through the use of either dominant-negative mutants, RNAi, or gene targeting, effectively abolishes Ang II-dependent NF-kappaB activation in hepatocytes. In addition, Bcl10(-/-) mice show defective hepatic cytokine production after Ang II treatment. Evidence also is presented that this pathway activates NF-kappaB through ubiquitination of IKKgamma, the regulatory subunit of the IkappaB kinase complex. These results elucidate a concrete series of molecular events that link ligand activation of the type 1 Ang II receptor to stimulation of the NF-kappaB transcription factor. These findings also uncover a function of the CARMA, Bcl10, and MALT1 proteins in cells outside the immune system.

Protective mechanism of Lygodium flexuosum extract in treating and preventing carbon tetrachloride induced hepatic fibrosis in rats

The protective effect of Lygodium flexuosum extract in preventive and curative treatments of CCl(4) induced fibrosis was quantified. Hepatic fibrosis was induced in male Wistar rats by CCl(4) administration (150 microL/100 gm rat weight, oral) twice a week for 10 weeks. In preventive treatment daily doses of L. flexuosum n-hexane extract (200 mg/kg, p.o) were administered for 10 weeks. In curative treatment L. flexuosum extract (200 mg/kg, p.o) was given for 2 weeks after the establishment of fibrosis for 10 weeks. Treatment with the n-hexane extract (200 mg/kg) reduced the mRNA levels of proinflammatory cytokines, growth factors and other signaling molecules, which are involved in hepatic fibrosis. The expression levels of tumor necrosis factor-alpha, interleukin-1beta, transforming growth factor-beta1, procollagen-I, procollagen-III and tissue inhibitor of metalloproteinase-1 were elevated during carbon tetrachloride administration and reduced the levels to normal by the treatment with the extract treatment. The increased levels of matrix metalloproteinase-13 in extract treated rats were indicative of the protective action of L. flexuosum n-hexane extract. In conclusion, L. flexuosum n-hexane extract functions as a potent fibrosuppresant, effectively reverses carbon tetrachloride-induced hepatic fibrosis in curative treatment and reduces the effects of ongoing toxic liver injury in preventive treatment by promoting extracellular matrix degradation in the fibrotic liver.

Upregulation of the tumor suppressor gene menin in hepatocellular carcinomas and its significance in fibrogenesis

The molecular mechanisms underlying the progression of cirrhosis toward hepatocellular carcinoma were investigated by a combination of DNA microarray analysis and literature data mining. By using a microarray screening of suppression subtractive hybridization cDNA libraries, we first analyzed genes differentially expressed in tumor and nontumor livers with cirrhosis from 15 patients with hepatocellular carcinomas. Seventy-four genes were similarly recovered in tumor (57.8% of differentially expressed genes) and adjacent nontumor tissues (64% of differentially expressed genes) compared with histologically normal livers. Gene ontology analyses revealed that downregulated genes (n = 35) were mostly associated with hepatic functions. Upregulated genes (n = 39) included both known genes associated with extracellular matrix remodeling, cell communication, metabolism, and post-transcriptional regulation gene (e.g., ZFP36L1), as well as the tumor suppressor gene menin (multiple endocrine neoplasia type 1; MEN1). MEN1 was further identified as an important node of a regulatory network graph that integrated array data with array-independent literature mining. Upregulation of MEN1 in tumor was confirmed in an independent set of samples and associated with tumor size (P = .016). In the underlying liver with cirrhosis, increased steady-state MEN1 mRNA levels were correlated with those of collagen alpha2(I) mRNA (P < .01). In addition, MEN1 expression was associated with hepatic stellate cell activation during fibrogenesis and involved in transforming growth factor beta (TGF-beta)-dependent collagen alpha2(I) regulation. In conclusion, menin is a key regulator of gene networks that are activated in fibrogenesis associated with hepatocellular carcinoma through the modulation of TGF-beta response.

Sustained activation of Rac1 in hepatic stellate cells promotes liver injury and fibrosis in mice

Rac, a small, GTP-binding protein in the Rho family, regulates several cellular functions, including the activation of NADPH oxidase, a major intracellular producer of reactive oxygen species (ROS). Hepatic stellate cells (HSCs) isolated from mice that are genetically deficient in NADPH oxidase produce less ROS, and their activation during chronic liver injury is abrogated, resulting in decreased liver fibrosis. Therefore, we hypothesized that HSC ROS production and activation would be enhanced, and fibrosis worsened, by increasing Rac expression in HSCs. To achieve this, we used transgenic mice that express constitutively active human Rac1 under the control of the alpha-smooth muscle actin (alpha-sma) promoter, because alpha-sma expression is induced spontaneously during HSC activation. Transgene expression was upregulated progressively during culture of primary Rac-transgenic HSCs, and this increased HSC ROS production as well as expression of activation markers and collagen. Similarly, Rac mice treated with carbon tetrachloride (CCl(4)) accumulated greater numbers of activated HSCs and had more liver damage, hepatocyte apoptosis, and liver fibrosis-as well as higher mortality-than CCl(4)-treated wild-type mice. In conclusion, sustained activation of Rac in HSCs perpetuates their activation and exacerbates toxin-induced liver injury and fibrosis, prompting speculation that Rac may be a therapeutic target in patients with cirrhosis.

A role for serotonin (5-HT) in hepatic stellate cell function and liver fibrosis

Hepatic stellate cells (HSCs) are key cellular components of hepatic wound healing and fibrosis. There is emerging evidence that the fibrogenic function of HSCs may be influenced by neurochemical and neurotrophic factors. This study addresses the potential for the serotonin (5-HT) system to influence HSC biology. Rat and human HSCs express the 5-HT1B, 5-HT1F 5-HT2A 5-HT2B, and 5-HT7 receptors, with expression of 5-HT1B 5-HT2A and 5-HT2B being induced on HSC activation. Induction of 5-HT2A and 5-HT2B was 106+/-39- and 52+/-8.5-fold that of quiescent cells, respectively. 5-HT2B was strongly associated with fibrotic tissue in diseased rat liver. Treatment of HSCs with 5-HT2 antagonists suppressed proliferation and elevated their rate of apoptosis; by contrast 5-HT was protective against nerve growth factor-induced apoptosis. 5-HT synergized with platelet-derived growth factor to stimulate increased HSC proliferation. HSCs were shown to express a functional serotonin transporter and to participate in both active uptake and release of 5-HT. We conclude that HSCs express key regulatory components of the 5-HT system enabling them to store and release 5-HT and to respond to the neurotransmitter in a profibrogenic manner. Antagonists that selectively target the 5-HT class of receptors may be exploited as antifibrotic drugs.

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Resolving fibrosis in the diseased liver: translating the scientific promise to the clinic

Liver fibrosis and its end-stage disease cirrhosis are a major cause of mortality and morbidity throughout the world. Fibrosis is a response to chronic liver injury or infection that if unabated leads to the replacement of normal functional liver tissue with scar tissue. Basic research over the past decade has generated a vastly improved knowledge of the cell and molecular biology of liver fibrosis that provides a framework on which to design and develop therapeutics. The field has also witnessed a genuine paradigm shift from the original dogma that liver fibrosis is only ever a progressive process, to the new understanding that liver fibrosis even in an advanced stage can be reversible. There is therefore renewed optimism that liver fibrosis may be cured providing that we develop therapies that halt the fibrogenic process and encourage the natural regenerative properties of the liver. The key to the design of effective therapeutics will be to exploit the ongoing discoveries pertaining to the biology and function of fibrogenic hepatic myofibroblasts and their interplay with other liver cells and with the hepatic extracellular matrix. This review provides a critique of those discoveries in basic research that provide the most promise for translation to the clinic. In addition, we review the latest developments in the search for minimal invasive diagnostic tests for fibrosis that will be essential for determining the efficacy of anti-fibrotic drugs.

Liver transduction with a simian virus 40 vector encoding insulin-like growth factor I reduces hepatic damage and the development of liver cirrhosis

Liver transplantation is the only treatment for advanced liver cirrhosis. Therapies halting the progression of the disease are urgently needed. Administration of recombinant insulin-like growth factor-I (rIGF-I) induces hepatoprotective effects in experimental cirrhosis. Therefore, we analyzed the efficacy of a recombinant simian virus 40 vector (rSV40) encoding IGF-I (rSVIGF-I) to prevent cirrhosis progression. First, transgene expression was evaluated in mice injected with rSV40 encoding luciferase, which showed long-term hepatic expression of the transgene. Interestingly, luciferase expression increased significantly in CCl(4)-damaged livers and upon IGF-I administration, thus liver injury and IGF-I expression from rSVIGF-I should favor transgene expression. rSVIGF-I therapeutic efficacy was studied in rats where liver cirrhosis was induced by CCl(4) inhalation during 36 weeks. At the end of the study, the hepatic levels of IGF-I and IGF-binding protein 3 were higher in rSVIGF-I-treated rats than in control cirrhotic animals. Cirrhotic rats treated with rSVIGF-I had reduced serum bilirubin, transaminases and liver fibrosis scores and increased hepatic expression of hepatocyte growth factor and STAT3alpha as compared to cirrhotic animals. Furthermore, cirrhotic animals showed testis atrophy and altered spermatogenesis, whereas testicular size and histology were normal in cirrhotic rats that received rSVIGF-I. Therefore, rSV40-mediated sustained expression of IGF-I in the liver slowed cirrhosis progression.

Four whole-istic aspects of schistosome granuloma biology: fractal arrangement, internal regulation, autopoietic component and closure

This paper centers on some whole-istic organizational and functional aspects of hepatic Schistosoma mansoni granuloma, which is an extremely complex system. First, it structurally develops a collagenic topology, originated bidirectionally from an inward and outward assembly of growth units. Inward growth appears to be originated from myofibroblasts derived from small portal vessel around intravascular entrapped eggs, while outward growth arises from hepatic stellate cells. The auto-assembly of the growth units defines the three-dimensional scaffold of the schistosome granulomas. The granuloma surface irregularity and its border presented fractal dimension equal to 1.58. Second, it is internally regulated by intricate networks of immuneneuroendocrine stimuli orchestrated by leptin and leptin receptors, substance P and Vasoactive intestinal peptide. Third, it can reach the population of +/- 40,000 cells and presents an autopoietic component evidenced by internal proliferation (Ki-67+ Cells), and by expression of c-Kit+ Cells, leptin and leptin receptor (Ob-R), granulocyte-colony stimulating factor (G-CSF-R), and erythropoietin (Epo-R) receptors. Fourth, the granulomas cells are intimately connected by pan-cadherins, occludin and connexin-43, building a state of closing (granuloma closure). In conclusion, the granuloma is characterized by transitory stages in such a way that its organized structure emerges as a global property which is greater than the sum of actions of its individual cells and extracellular matrix components.

Hepatic histology in obese patients undergoing bariatric surgery

BACKGROUND/AIMS

Obesity is one of the most important clinical associations with non-alcoholic steatohepatitis (NASH). Our aim was to assess the prevalence of non-alcoholic fatty liver disease (NAFLD)/NASH in morbidly obese patients and the risk factors to more aggressive liver disease in this population.

METHODS

Review of available studies on prevalence of NAFLD/NASH in severely obese patients submitted to bariatric surgery.

RESULTS

Twelve observational and transversal studies were included, with consecutive recruitment, and prospective evaluation of data, summing 1620 patients with severe obesity. Prevalence of steatosis and NASH was 91% (range: 85-98%) and 37% (24-98%), respectively, with unexpected cirrhosis in 1.7% (1-7%). NASH was not related with age or body mass index, but there was an association between male sex and NASH/hepatic fibrosis. Diabetes mellitus and insulin resistance were the conditions most frequently associated with NASH, and hypertension with advanced hepatic fibrosis.

CONCLUSIONS

There is a very high prevalence of NAFLD in asymptomatic morbidly obese patients, more than one-third presenting histological criteria for NASH. This review underscores the large variations in prevalence of NASH between studies, calling for the need for a better agreement in the use of the histological criteria.

Fibrosis as an end point for clinical trials in liver disease: a report of the international fibrosis group

Deaths due to the consequences of advanced liver fibrosis and cirrhosis remain a significant cause of mortality worldwide. Biologically plausible pathways involved in hepatic fibrogenesis have also led to the identification of numerous preclinical and clinical compounds that have received great interest as potential future therapeutic agents for patients with liver fibrosis. With this in mind, stake holders from academia, regulatory agencies, clinicians, and the pharmaceutical industry met to understand and discuss the many complex issues involved in developing potential therapeutic agents which act primarily through modifying fibrosis and to discuss appropriate end points for clinical trials in these patient populations. In this article, we summarize those discussions and attempt to highlight many of the hurdles and unanswered questions as we attempt to move forward and develop therapies to combat liver fibrosis.

PPARgamma agonists prevent TGFbeta1/Smad3-signaling in human hepatic stellate cells

PPARgamma agonists inhibit liver fibrosis, but the mechanisms involved are uncertain. We hypothesized that PPARgamma agonists inhibit transforming growth factor (TGF)beta1-activation of TGFbeta receptor (TGFbetaR)-1 signaling in quiescent stellate cells, thereby abrogating Smad3-dependent induction of extracellular matrix (ECM) genes, such as PAI-1 and collagen-1alphaI. To test this, human HSC were cultured to induce a quiescent phenotype, characterized by lipid accumulation and PPARgamma expression and transcriptional activity. These adipocytic HSC were then treated with TGFbeta1+/-a TGFbetaR-1 kinase inhibitor (SB431542) or a PPARgamma agonist (GW7845). TGFbeta1 caused dose- and time-dependent increases in Smad3 phosphorylation, followed by induction of collagen and PAI-1 expression. Like the TGFbetaR-1 kinase inhibitor, the PPARgamma agonist caused dose-dependent inhibition of all of these responses without effecting HSC proliferation or viability. Thus, the anti-fibrotic actions of PPARgamma agonists reflect their ability to inhibit TGFbeta1-TGFbetaR1 signaling that initiates ECM gene expression in quiescent HSC.

Integration of technologies for hepatic tissue engineering

The liver is the largest internal organ in the body, responsible for over 500 metabolic, regulatory, and immune functions. Loss of liver function leads to liver failure which causes over 25,000 deaths/year in the United States. Efforts in the field of hepatic tissue engineering include the design of bioartificial liver systems to prolong patient's lives during liver failure, for drug toxicity screening and for the study of liver regeneration, ischemia/reperfusion injury, fibrosis, viral infection, and inflammation. This chapter will overview the current state-of-the-art in hepatology including isolated perfused liver, culture of liver slices and tissue explants, hepatocyte culture on collagen "sandwich" and spheroids, coculture of hepatocytes with non-parenchymal cells, and the integration of these culture techniques with microfluidics and reactor design. This work will discuss the role of oxygen and medium composition in hepatocyte culture and present promising new technologies for hepatocyte proliferation and function. We will also discuss liver development, architecture, and function as they relate to these culture techniques. Finally, we will review current opportunities and major challenges in integrating cell culture, bioreactor design, and microtechnology to develop new systems for novel applications.

Modern pathogenetic concepts of liver fibrosis suggest stellate cells and TGF-beta as major players and therapeutic targets

Hepatic fibrosis is a scarring process that is associated with an increased and altered deposition of extracellular matrix in liver. At the cellular and molecular level, this progressive process is mainly characterized by cellular activation of hepatic stellate cells and aberrant activity of transforming growth factor-beta1 and its downstream cellular mediators. Although the cellular responses to this cytokine are complex, the signalling pathways of this pivotal cytokine during the fibrogenic response and its connection to other signal cascades are now understood in some detail. Based on the current advances in understanding the pleiotropic reactions during fibrogenesis, various inhibitors of transforming growth factor-beta were developed and are now being investigated as potential drug candidates in experimental models of hepatic injury. Although it is too early to favour one of these antagonists for the treatment of hepatic fibrogenesis in human, the experimental results obtained yet provide stimulatory impulses for the development of an effective treatment of choice in the not too distant future. The present review summarises the actual knowledge on the pathogenesis of hepatic fibrogenesis, the role of transforming growth factor-beta and its signalling pathways in promoting the fibrogenic response, and the therapeutic modalities that are presently in the spotlight of many investigations and are already on the way to take the plunge into clinical studies.

Modern pathogenetic concepts of liver fibrosis suggest stellate cells and TGF-beta as major players and therapeutic targets

Hepatic fibrosis is a scarring process that is associated with an increased and altered deposition of extracellular matrix in liver. At the cellular and molecular level, this progressive process is mainly characterized by cellular activation of hepatic stellate cells and aberrant activity of transforming growth factor-beta1 and its downstream cellular mediators. Although the cellular responses to this cytokine are complex, the signalling pathways of this pivotal cytokine during the fibrogenic response and its connection to other signal cascades are now understood in some detail. Based on the current advances in understanding the pleiotropic reactions during fibrogenesis, various inhibitors of transforming growth factor-beta were developed and are now being investigated as potential drug candidates in experimental models of hepatic injury. Although it is too early to favour one of these antagonists for the treatment of hepatic fibrogenesis in human, the experimental results obtained yet provide stimulatory impulses for the development of an effective treatment of choice in the not too distant future. The present review summarises the actual knowledge on the pathogenesis of hepatic fibrogenesis, the role of transforming growth factor-beta and its signalling pathways in promoting the fibrogenic response, and the therapeutic modalities that are presently in the spotlight of many investigations and are already on the way to take the plunge into clinical studies.

Modern pathogenetic concepts of liver fibrosis suggest stellate cells and TGF-beta as major players and therapeutic targets

Hepatic fibrosis is a scarring process that is associated with an increased and altered deposition of extracellular matrix in liver. At the cellular and molecular level, this progressive process is mainly characterized by cellular activation of hepatic stellate cells and aberrant activity of transforming growth factor-beta1 and its downstream cellular mediators. Although the cellular responses to this cytokine are complex, the signalling pathways of this pivotal cytokine during the fibrogenic response and its connection to other signal cascades are now understood in some detail. Based on the current advances in understanding the pleiotropic reactions during fibrogenesis, various inhibitors of transforming growth factor-beta were developed and are now being investigated as potential drug candidates in experimental models of hepatic injury. Although it is too early to favour one of these antagonists for the treatment of hepatic fibrogenesis in human, the experimental results obtained yet provide stimulatory impulses for the development of an effective treatment of choice in the not too distant future. The present review summarises the actual knowledge on the pathogenesis of hepatic fibrogenesis, the role of transforming growth factor-beta and its signalling pathways in promoting the fibrogenic response, and the therapeutic modalities that are presently in the spotlight of many investigations and are already on the way to take the plunge into clinical studies.

Analysis of gene expression changes in relation to toxicity and tumorigenesis in the livers of Big Blue transgenic rats fed comfrey (Symphytum officinale)

Background

Comfrey is consumed by humans as a vegetable and a tea, and has been used as an herbal medicine for more than 2000 years. Comfrey, however, is hepatotoxic in livestock and humans and carcinogenic in experimental animals. Our previous study suggested that comfrey induces liver tumors by a genotoxic mechanism and that the pyrrolizidine alkaloids in the plant are responsible for mutation induction and tumor initiation in rat liver.

Results

In this study, we identified comfrey-induced gene expression profile in the livers of rats. Groups of 6 male transgenic Big Blue rats were fed a basal diet and a diet containing 8% comfrey roots, a dose that resulted in liver tumors in a previous carcinogenicity bioassay. The animals were treated for 12 weeks and sacrificed one day after the final treatment. We used a rat microarray containing 26,857 genes to perform genome-wide gene expression studies. Dietary comfrey resulted in marked changes in liver gene expression, as well as in significant decreases in the body weight and increases in liver mutant frequency. When a two-fold cutoff value and a P-value less than 0.01 were selected, 2,726 genes were identified as differentially expressed in comfrey-fed rats compared to control animals. Among these genes, there were 1,617 genes associated by Ingenuity Pathway Analysis with particular functions, and the differentially expressed genes in comfrey-fed rat livers were involved in metabolism, injury of endothelial cells, and liver injury and abnormalities, including liver fibrosis and cancer development.

Conclusion

The gene expression profile provides us a better understanding of underlying mechanisms for comfrey-induced hepatic toxicity. Integration of gene expression changes with known pathological changes can be used to formulate a mechanistic scheme for comfrey-induced liver toxicity and tumorigenesis.

Natural compounds from danshen suppress the activity of hepatic stellate cells

Danshen is an herbal medication frequently used in oriental medicine to treat liver or kidney malfunction. In the course of our studies, we observed that compounds purified from Danshen exhibit an inhibitory activity against Discoidin Domain Receptor 2 (DDR2) tyrosine kinase. Through this inhibition, these compounds also inhibited the growth of HSC T6 cells and suppressed the expression of alpha-smooth muscle actin and MMP2, as well as collagen synthesis, all of which are increased in activated liver stellate cells. Given that activation of liver stellate cells is the hallmark of liver fibrosis and that DDR2 plays a critical role in this activation, these results suggest that one of the pharmacological activities of Danshen extract that protects the liver is the inhibition of key cell-signaling kinases, such as DDR2, in liver stellate cells.

Pancreas recovery following cerulein-induced pancreatitis is impaired in plasminogen-deficient mice

BACKGROUND & AIMS

The plasminogen (plg) system participates in tissue repair in several organs, but its role in pancreas repair remains poorly characterized. To understand better the role of plg in pancreas recovery following injury, we examined the course of cerulein-induced pancreatitis in plg-deficient and -sufficient mice.

METHODS

Pancreatitis was induced by cerulein administration (50 microg/kg, 7 intraperitoneal injections). Mice were killed either at the acute phase (7 hours after the first cerulein injection) or during recovery (at 2, 4, and 7 days). In pancreatic sections, we examined pancreatic morphology, trypsin activation, inflammatory cell infiltration, acinar cell death, cell proliferation, extracellular matrix deposition, activation of stellate cells (PSCs), and components of the plg and metalloproteinase systems.

RESULTS

In plg-sufficient mice, pancreatic plg levels and plasmin activity increased during the acute phase and remained elevated during recovery. Pancreatitis resolved in plg-sufficient mice within 7 days. Pancreas recovery involved reorganization of the parenchyma structure, removal of necrotic debris, cell proliferation, transient activation of PSCs, and moderate deposition of extracellular matrix proteins. Acute pancreatitis (7 hours) was indistinguishable between plg-deficient and -sufficient mice. In contrast, pancreas recovery was impaired in plg-deficient mice. Plg deficiency led to disorganized parenchyma, extensive acinar cell loss, poor removal of necrotic debris, reduced cell proliferation, and fibrosis. Fibrosis was characterized by deposition of collagens and fibronectin, persistent activation of PSCs, and up-regulation of pancreatic transforming growth factor beta1.

CONCLUSIONS

Plg/plasmin deficiency leads to features similar to those found in chronic pancreatitis such as parenchymal atrophy and fibrosis.

Bone marrow-derived fibrocytes participate in pathogenesis of liver fibrosis

BACKGROUND/AIMS

Hepatic stellate cells (HSCs) play a key role in hepatic fibrogenesis. However, their origin is still unknown. We tested the hypothesis that bone marrow (BM) contributes to the population of HSCs.

METHODS

Chimeric mice transplanted with donor BM from collagen alpha1(I)-GFP+ reporter mice were subjected to the bile duct ligation (BDL)-induced liver injury.

RESULTS

In response to injury, BM-derived collagen-expressing GFP+ cells were detected in liver tissues of chimeric mice. However, these cells were not activated HSCs in that they did not express alpha-smooth muscle actin or desmin and could not be isolated with the HSC fraction. Meanwhile, the majority of these BM-derived cells co-expressed collagen-GFP+ and CD45+, suggesting that these cells represent a unique population of fibrocytes. Consistent with their lymphoid origin, the number of GFP+CD45+ fibrocytes found in BM and spleen of chimeric mice increased in response to injury. Fibrocytes cultured in the presence of TGF-beta1 differentiated into SMA+desmin+ collagen-producing myofibroblasts, potentially contributing to liver fibrosis.

CONCLUSIONS

In response to the BDL-induced liver injury: (i) HSCs do not originate in the BM; (ii) collagen-producing fibrocytes are recruited from the BM to damaged liver.

Overexpression of Bcl-2 by activated human hepatic stellate cells: resistance to apoptosis as a mechanism of progressive hepatic fibrogenesis in humans

BACKGROUND AND AIMS

Myofibroblast-like cells, originating from activation of hepatic stellate cells (HSC/MFs), play a key role in liver fibrosis, a potentially reversible process that may rely on induction of HSC/MFs apoptosis. While this possibility has been shown in cultured rat HSC, very limited data are currently available for human HSC/MFs.

METHODS

Cultured human HSC/MFs were exposed to several proapoptotic stimuli, including those known to induce apoptosis in rat HSC/MFs, and induction of cell death and related mechanisms were investigated using morphology, molecular biology, and biochemical techniques.

RESULTS

In this study we report that fully activated human HSC/MFs did not undergo spontaneous apoptosis and survived to prolonged serum deprivation, Fas activation, or exposure to nerve growth factor, tumour necrosis factor alpha (TNF-alpha), oxidative stress mediators, doxorubicin, and etoposide. Induction of caspase dependent, mitochondria driven apoptosis in HSC/MFs was observed only when protein synthesis or transcription were inhibited. Importantly, the process of HSC activation was accompanied by changes in expression of a set of genes involved in apoptosis control. In particular, activated human HSC/MFs in culture overexpressed Bcl-2. The role of Bcl-2 was crucial as Bcl-2 silenced cells became susceptible to TNF-alpha induced apoptosis. Finally, Bcl-2 was markedly expressed in HSC/MFs present in liver tissue obtained from patients with hepatitis C virus related cirrhosis.

CONCLUSIONS

Human activated HSC/MFs are resistant to most proapoptotic stimuli due to Bcl-2 overexpression and this feature may play a key role in the progression of fibrosis in chronic liver diseases.

Human hepatic stellate cells are resistant to apoptosis: implications for human fibrogenic liver disease

Resistance of hepatic stellate cells or myofibroblasts to proapoptotic stimuli is different between rodent and human cells. This may be important when looking for antifibrotic agents that can be used in human liver fibrosis

Loss of MMP 13 attenuates murine hepatic injury and fibrosis during cholestasis

Cholestasis occurs in a variety of clinical settings and often results in liver injury and secondary biliary fibrosis. Several matrix metalloproteinases (MMPs) are upregulated in the liver during cholestasis. The function of the major interstitial collagenase, MMP-13, in the initial phase of liver fibrosis is unknown. The aim of this study was to evaluate the role of MMP-13 during the development of cholestasis-induced liver fibrosis by comparing wild-type and MMP-13-deficient mice. Cholestasis was induced by bile duct ligation (BDL) for 5 days or 3 weeks. Activation and proliferation of hepatic stellate cells (HSCs) were detected by immunohistochemistry. Expression of MMP-13 mRNA increased significantly in BDL livers of WT mice. After BDL for 3 weeks liver fibrosis was suppressed in MMP-13-deficient mice versus WT animals. Activation and proliferation of HSCs were also suppressed in livers of MMP-13-deficient mice after BDL. To clarify the mechanism of this suppression, samples from 5-day BDL mice were used for evaluation of liver injury. Compared with those in WT animals, serum ALT and the number of hepatic neutrophils were reduced in MMP-13-deficient mice. Increased expression of the mRNA of inflammatory mediators such as tumor necrosis factor-alpha (TNF-alpha) was significantly suppressed in livers of MMP-13-deficient mice. Upregulation of fibrogenic markers, for example, transforming growth factor beta1 (TGF-beta1), was also significantly suppressed in livers of MMP-13-deficient mice versus in WT mice. In conclusion, distinct from the known function of interstitial collagenase to reduce liver fibrosis by degrading the extracellular matrix, MMP-13 contributes to accelerating fibrogenesis in cholestatic livers by mediating the initial inflammation of the liver.

Effects of interferon plus ribavirin treatment on NF-kappaB, TGF-beta1, and metalloproteinase activity in chronic hepatitis C

Little is known about the cellular and molecular mechanisms underlying the effects of anti-viral therapy on the regression of liver inflammation and fibrosis in chronic hepatitis C. The aim of this study was to evaluate the effects of interferon alpha and ribavirin in combination therapy on the tissue expression of nuclear-factor kB (NF-kappaB) (a transcription factor coordinating the expression of stress genes involved in immune response and inflammation), of the polypeptide transforming growth factor beta-1 (TGF-beta1) and matrix metalloproteinases 1 (MMP-1) (both of which play an important part in the pathological process of liver fibrogenesis), and on the serum levels of soluble TGF-beta1, tissue inhibitors of metalloproteinases (TIMP)-1, and active endogenous MMP-2 and MMP-9 in paired (pre- and post-treatment) liver biopsy and serum samples of subjects with chronic hepatitis C. Serum levels of TGF-beta1, TIMP-1, MMP-2, and MMP-9 were evaluated by enzyme-linked immunosorbent assay. Liver expression of muscle-specific alpha-actin, NF-kappaB, TGF-beta1, and MMP-1 was studied immunohistochemically using commercially available mono- and polyclonal antisera in an avidin-biotin complex method. Combination therapy induced a reduction in the liver expression of TGF-beta and NF-kappaB and an increased expression of MMP-1, regardless of the virological response to the treatment. The greater expression of MMP-1 and lesser expression of NF-kappaB were both associated with an improvement in fibrosis score. These effects paralleled the significant increase in soluble MMP-9/TIMP-1 ratio in post-therapy sera. Combination therapy with interferon and ribavirin affects the tissue expression of TGF-beta-1 and NF-kappaB and favors metalloproteinase activity, and may thereby modulate hepatic fibrogenetic events.

Do we still need a liver biopsy? Are the serum fibrosis tests ready for prime time?

Liver biopsy has been in use for more than a century for diagnosis and staging of acute and chronic liver diseases. Several serum markers and panels offer the opportunity to assess the extent of liver disease noninvasively and spare some patients the risks associated with percutaneous liver biopsy, but only a few of the noninvasive serum markers allow the determination of different stages of fibrosis on a continuum similar to that achieved with liver biopsy. This article reviews the results of recent published and preliminary studies on serum markers, focusing on their comparison with liver biopsy and their clinical utility.

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Assessment of liver fibrosis by a noninvasive method of transient elastography and biochemical markers

AIM: To assess the correlation between the fibrotic area (FA) as calculated by a digital image analysis (DIA), and to compare the diagnostic accuracy of FibroScan to the other existing Liver fibrosis (LF) markers using the receiver operating curve analysis.

METHODS: We recruited 30 patients who underwent a liver resection for three different etiologies including normal liver, hepatitis B, and hepatitis C. Liver stiffness was measured by using a FibroScan. The FA was then calculated by DIA to evaluate LF in order to avoid any sampling bias.

RESULTS: The FA negatively correlated with Prothrom-bin time (PT), platelet count, lecithin-cholesterol acyltransferase (LCAT), and pre-albumin (ALB). On the other hand, the findings of FibroScan correlated with similar markers. The FA positively correlated with FibroScan, serum hyaluronate level, and type IV collagen level, and aspartate transaminase to platelet ratio index (APRI). The area under the receiver operating curve for FibroScan was higher than that for the other markers, even though the statistical significance was minimal.

CONCLUSION: Our findings suggest that FibroScan can initially be used to assess LF as an alternative to a liver biopsy (LB) and serum diagnosis, because it is a safe method with comparable diagnostic accuracy regarding the existing LF markers.

Alpha-melanocyte-stimulating hormone gene therapy reverses carbon tetrachloride induced liver fibrosis in mice

BACKGROUND

Hepatic fibrosis represents a process of healing and scarring in response to chronic liver injury. Effective therapies are lacking. We have previously demonstrated that alpha-melanocyte-stimulating hormone (alpha-MSH) gene therapy protects against thioacetamide-induced acute liver failure in mice. Recent reports showed that collagen metabolism is a novel target of alpha-MSH. Therefore, the aim of this study is to investigate whether alpha-MSH gene therapy possesses anti-hepatic fibrogenic effect in mice.

METHODS

Liver fibrosis was induced in mice by administering carbon tetrachloride (CCl4) continuously for 10 weeks. Alpha-MSH expression plasmid was delivered via electroporation after liver fibrosis had been established. Histopathology, reverse-transcription polymerase chain reaction (RT-PCR), immunoblotting, and gelatin zymography were used to investigate its possible mechanisms of action.

RESULTS

Alpha-MSH gene therapy reversed established liver fibrosis in CCl4-treated mice. RT-PCR revealed that alpha-MSH gene therapy attenuated the liver TGF-beta1, collagen alpha1, and cell adhesion molecule mRNA upregulation. Following gene transfer, both the activation of alpha-smooth muscle actin (alpha-SMA) and cyclooxygenase-2 (COX-2) was significantly attenuated. Further, alpha-MSH significantly increased matrix metalloproteinase (MMP) activity with tissue inhibitors of matrix metalloproteinase (TIMP) inactivation.

CONCLUSIONS

We have demonstrated that alpha-MSH gene therapy reversed established liver fibrosis in mice. It also prevented the upregulated fibrogenic and proinflammatory gene response after CCl4 administration. Its collagenolytic effect may be attributed to MMP and TIMP modulation. In summary, alpha-MSH gene therapy may be an effective therapeutic modality against liver fibrosis with potential clinical use.

Expression of inducible nitric oxide (NO) synthase but not prevention by its gene ablation of hepatocarcinogenesis with fibrosis caused by a choline-deficient, L-amino acid-defined diet in rats and mice

Expression of inducible nitric oxide synthase (iNOS) and effects of iNOS gene ablation on the hepatocarcinogenesis associated with fibrosis caused by a choline-deficient, L-amino acid-defined (CDAA) diet, were examined in male F344 rats and C57BL/6J wild-type and iNOS-/- mice. Western blot, RT-PCR and immunohistochemical analyses revealed increased expression of iNOS protein and mRNA in the livers of rats and wild-type mice fed a CDAA diet for 12-80 weeks, associated with elevated serum NO(x) and liver nitrotyrosine levels. iNOS-/- mice demonstrated greater liver injury and fibrosis in the early stage than their wild-type counterparts, but this did not significantly affect the incidence and multiplicity of altered foci, adenomas and hepatocellular carcinomas in spite of immunohistochemical iNOS expression in these lesions. Results suggested no major determinant roles of the expressed iNOS in the development of liver tumors caused by the CDAA diet.

Crosstalk between PDGF and IGF-I receptors in rat liver myofibroblasts: implication for liver fibrogenesis

Insulin-like growth factor I (IGF-I) and platelet-derived growth factor (PDGF) have been identified as significant mitogens for liver myofibroblasts (LMFs), one of the cell populations playing a role in liver fibrogenesis. In the present work, we aimed to elucidate a possible interaction between PDGF receptor (PDGFR) and IGF-I receptor (IGF-IR) signaling in LMFs. Among different rat liver cells, PDGFR alpha- and beta-subunits were mainly expressed in hepatic stellate cells and LMFs, and were upregulated during their in vitro cultivation. In LMFs, PDGF-BB (10 ng/ml) stimulated DNA synthesis approximately two-fold and this effect was similar to that of IGF-I. IGF-I and PDGF-BB differentially affected IGF-IR and PDGFR signaling. High concentrations of IGF-I decreased levels of IGF-IR and IRS-1 and inhibited the expression and activation of PDGFRalpha. PDGF-BB prevented IGF-I-induced downregulation of the IGF-IR, but did not affect expression of its cognate receptor subunits. Transphosphorylation of PDGFR and IGF-IR was not observed. PDGF effectively activated terminal MAP kinases, PI3 kinase and Akt kinase, whereas IGF-I demonstrated weaker effects. PLCgamma(1) was phosphorylated only in response to PDGF, but not to IGF-I. In rat LMFs, blockade of the IGF-IR via inhibition of the IGF-IR kinase completely abrogated IGF- and PDGF-induced mitogenesis and the ability of PDGF to phosphorylate PLCgamma(1). In conclusion, the presented data demonstrate that the PDGFR signaling requires a functional IGF-IR and that PDGF-BB stabilizes the IGF-IR function through preventing the IGF-I-induced downregulation of the IGF-IR. These interactions might be relevant in vivo for the fibroproliferative response during liver injury.

Elevated levels of von Willebrand Factor in cirrhosis support platelet adhesion despite reduced functional capacity

Cirrhosis of the liver is frequently accompanied by complex alterations in the hemostatic system, resulting in a bleeding tendency. Although many hemostatic changes in liver disease promote bleeding, compensatory mechanisms also are found, including high levels of the platelet adhesive protein von Willebrand Factor (VWF). However, conflicting reports on the functional properties of VWF in cirrhosis have appeared in literature. We have measured a panel of VWF parameters in plasma from patients with cirrhosis of varying severity and causes. Furthermore, we assessed the contribution of VWF to platelet adhesion, by measuring the ability of plasma from patients with cirrhosis to support adhesion of normal or patient platelets under flow conditions. VWF antigen levels were strongly increased in patients with cirrhosis. In contrast, the relative collagen binding activity, as well as the relative ristocetin cofactor activity, was significantly lower in patients as compared with controls, indicating loss of function. Accordingly, patients had a reduced fraction of high-molecular-weight VWF multimers. Both strongly elevated and reduced activity and antigen levels of the VWF cleaving protease ADAMTS13 were found in individual patients. Adhesion of either normal or patient platelets to a collagen surface was substantially increased when these platelets were resuspended in plasma of patients with cirrhosis, as compared with control plasma. In conclusion, highly elevated levels of VWF in patients with cirrhosis contribute to the induction of primary hemostasis despite reduced functional properties of the molecule. This phenomenon might compensate for defects in platelet number and function in patients with cirrhosis.

Thiazolidinediones and hepatic fibrosis: don't wait too long

Lack of effect of delayed thiazolidinedione treatment may imply that these drugs are of limited efficacy in hepatic fibrosis, and that treatment of chronic liver disease might be successful only if the therapy were started very early

Fibrosis in heart disease: understanding the role of transforming growth factor-beta in cardiomyopathy, valvular disease and arrhythmia

The importance of fibrosis in organ pathology and dysfunction appears to be increasingly relevant to a variety of distinct diseases. In particular, a number of different cardiac pathologies seem to be caused by a common fibrotic process. Within the heart, this fibrosis is thought to be partially mediated by transforming growth factor-beta1 (TGF-beta1), a potent stimulator of collagen-producing cardiac fibroblasts. Previously, TGF-beta1 had been implicated solely as a modulator of the myocardial remodelling seen after infarction. However, recent studies indicate that dilated, ischaemic and hypertrophic cardiomyopathies are all associated with raised levels of TGF-beta1. In fact, the pathogenic effects of TGF-beta1 have now been suggested to play a major role in valvular disease and arrhythmia, particularly atrial fibrillation. Thus far, medical therapy targeting TGF-beta1 has shown promise in a multitude of heart diseases. These therapies provide great hope, not only for treatment of symptoms but also for prevention of cardiac pathology as well. As is stated in the introduction, most reviews have focused on the effects of cytokines in remodelling after myocardial infarction. This article attempts to underline the significance of TGF-beta1 not only in the post-ischaemic setting, but also in dilated and hypertrophic cardiomyopathies, valvular diseases and arrhythmias (focusing on atrial fibrillation). It also aims to show that TGF-beta1 is an appropriate target for therapy in a variety of cardiovascular diseases.

Gene expression profiling defined pathways correlated with fibroblast cell proliferation induced by Opisthorchis viverrini excretory/secretory product

AIM: To investigate the mechanism of fibroblast cell proliferation stimulated by the Opisthorchis viverrini excretory/secretory (ES) product.

METHODS: NIH-3T3, mouse fibroblast cells were treated with O. viverrini ES product by non-contact co-cultured with the adult parasites. Total RNA from NIH-3T3 treated and untreated with O. viverrini was extracted, reverse transcribed and hybridized with the mouse 15K complementary DNA (cDNA) array. The result was analyzed by ArrayVision version 5 and GeneSpring version 5 softwares. After normalization, the ratios of gene expression of parasite treated to untreated NIH-3T3 cells of 2-and more-fold upregulated was defined as the differentially expressed genes. The expression levels of the signal transduction genes were validated by semi-quantitative SYBR-based real-time RT-PCR.

RESULTS: Among a total of 15 000 genes/ESTs, 239 genes with established cell proliferation-related function were 2 fold-and more-up-regulated by O. viverrini ES product compared to those in cells without exposure to the parasitic product. These genes were classified into groups including energy and metabolism, signal transduction, protein synthesis and translation, matrix and structural protein, transcription control, cell cycle and DNA replication. Moreover, the expressions of serine-threonine kinase receptor, receptor tyrosine kinase and collagen production-related genes were up-regulated by O. viverrini ES product. The expression level of signal transduction genes; pkC, pdgfrα, jak 1, eps 8, tgfβ 1i4, strap and h ras measured by real-time RT-PCR confirmed their expression levels to those obtained from cDNA array. However, only the up-regulated expression of pkC, eps 8 and tgfβ 1i4 which are the downstream signaling molecules of either epidermal growth factor (EGF) or transforming growth factor-β (TGF-β) showed statistical significance (P < 0.05).

CONCLUSION: O. viverrini ES product stimulates the significant changes of gene expression in several functional categories and these mainly include transcripts related to cell proliferation. The TGF-β and EGF signal transduction pathways are indicated as the possible pathways of O. viverrini-driven cell proliferation.

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Cryoglobulinemia is associated with steatosis and fibrosis in chronic hepatitis C

The relationship between cryoglobulin and severity of liver lesions is debated. No study has focused on the relationship between cryoglobulin, liver steatosis, and fibrosis. The aim of this study was to determine the relationship between cryoglobulins and liver lesions (necroinflammation, fibrosis, and steatosis) in patients with hepatitis C virus (HCV) infection. Four hundred and thirty-seven consecutive patients with untreated chronic hepatitis C who had been admitted for liver biopsy were included in the study. Risk factors for fibrosis and steatosis were assessed. The mean age was 50.9 +/- 13.8 years, and 49% were male. Cryoglobulin was present in 286 patients, 103 of whom had vasculitis. One hundred and eighty-six patients (43%) had steatosis greater than 10%, and 110 (25%) had advanced fibrosis (Metavir score F3-F4). On multivariate analysis, cryoglobulin increased by nearly threefold the risk of having advanced fibrosis and steatosis greater than 10%. Steatosis greater than 10% was associated with a higher body mass index (P < .001), HCV genotype 3 (P < .001), cryoglobulin (P = .002), and advanced liver fibrosis (P = .009). Advanced fibrosis (F3-F4) was associated with a higher level of gamma-glutamyltransferase (P = .04), cryoglobulin (P < .001), a high grade of necroinflammation (Metavir score A2-A3) (P < .001), and steatosis higher than 10% (P = .04). In conclusion, our study shows an independent association between cryoglobulin and steatosis as well as advanced fibrosis.

The role of integrin-linked kinase in liver wound healing

Liver wound healing is an integrated process in which hepatic stellate cells play a major role. We hypothesized that the cellextracellular signaling protein integrin-linked kinase (ILK) is important in transducing signals from the extracellular matrix to stellate cells and thus plays a critical role in stellate cell activation and fibrogenesis during liver injury. Liver injury and subsequent stellate cell activation led to a 3-fold increase in ILK expression and increased kinase activity. Overexpression of ILK in isolated stellate cells led to enhanced motility and adhesion as well as increases in smooth muscle alpha-actin and type I collagen mRNA expression. The effects of ILK on stellate cell phenotypes were phosphatidylinositol 3-kinase-dependent. Forced expression of ILK in vivo led to increases in type I collagen, smooth muscle alpha-actin, transforming growth factor-beta, and extra domain A (EDA) fibronectin mRNAs (by 3.2-, 3.5-, 2.5-, and 2.2-fold, respectively; n = 8, p < 0.05 for each versus the control), whereas inhibition of ILK in vivo led to significant reductions in these mRNAs. Morphometric analysis revealed that ILK overexpression led to a 31.4% increase in liver collagen content (n = 8, p < 0.05 versus the control); in contrast ILK knockdown in vivo led to a significant reduction in fibrogenesis. We conclude that ILK plays an important pathophysiological role in vivo in liver wound healing.

Localization of the sulfate/anion exchanger in the rat liver

Although the sulfate/anion transporter (sat-1; SLC26A1) was isolated from a rat liver cDNA library by expression cloning, localization of sat-1 within the liver and its contribution to the transport of sulfate and organo sulfates have remained unresolved. In situ hybridization and immunohistochemical studies were undertaken to demonstrate the localization of sat-1 in liver tissue. RT-PCR studies on isolated hepatocytes and liver endothelial and stellate cells in culture were performed to test for the presence of sat-1 in these cells. In sulfate uptake and efflux experiments, the substrate specificity of sat-1 was evaluated. Sat-1 mRNA was found in hepatocytes and endothelial cells. Sat-1 protein was localized in sinusoidal membranes and along the borders of hepatocytes. The canalicular region and bile capillaries were not stained. Sulfate uptake was only slightly affected by sulfamoyl diuretics or organo sulfates. Sulfate efflux from sat-1-expressing oocytes was enhanced in the presence of bicarbonate, indicating sulfate/bicarbonate exchange. Estrone sulfate was not transported by sat-1. Sat-1 may be responsible for the uptake of inorganic sulfate from the blood into hepatocytes to enable sulfation reactions. In hepatocytes and endothelial cells, sat-1 may also supply sulfate for proteoglycan synthesis.

Filtrate of fermented mycelia from Antrodia camphorata reduces liver fibrosis induced by carbon tetrachloride in rats

AIM: To investigate the effects of filtrate of fermented mycelia from Antrodia camphorata (FMAC) on liver fibrosis induced by carbon tetrachloride (CCl₄) in rats.

METHODS: Forty Wistar rats were divided randomly into control group and model group. All model rats were given 200 mL/L CCl₄ (2 mL/Kg, po) twice a week for 8 wk. Four weeks after CCl₄ treatment, thirty model rats were further divided randomly into 3 subgroups: CCl₄ and two FMAC subgroups. Rats in CCl₄ and 2 FMAC subgroups were treated with FMAC 0, 0.5 and 1.0 g/kg, daily via gastrogavage beginning at the fifth week and the end of the eighth week. Spleen weight, blood synthetic markers (albumin and prothrombin time) and hepatic malondialdehyde (MDA) and hydroxyproline (HP) concentrations were determined. Expression of collagen I, tissue inhibitor of metalloproteinases (TIMP)-1 and transforming growth factor β1 (TGF-β1) mRNA were detected by RT-PCR. Histochemical staining of Masson’s trichrome was performed.

RESULTS: CCl₄ caused liver fibrosis, featuring increased prothrombin time, hepatic MDA and HP contents, and spleen weight and decreased plasma albumin level. Compared with CCl₄ subgroup, FMAC subgroup (1 g/kg) significantly decreased the prothrombin time (36.7 ± 7.2 and 25.1 ± 10.2 in CCl₄ and FMAC groups, respectively, P < 0.05) and increased plasma albumin concentration (22.7 ± 1.0 and 30.7 ± 2.5 in CCl₄ and FMAC groups, respectively, P  < 0.05). Spleen weight was significantly lower in rats treated with CCl₄ and FMAC (1 g/kg) compared to CCl₄ treated rats only (2.7 ± 0.1 and 2.4 ± 0.2 in CCl₄ and FMAC groups, respectively, P  < 0.05). The amounts of hepatic MDA and HP in CCl₄ ± FAMC (1 g/kg) subgroup were also lower than those in CCl₄ subgroup (MDA: 3.9 ± 0.1 and 2.4 ± 0.6 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01; HP: 1730.7 ± 258.0 and 1311.5 ± 238.8 in CCl₄ and CCl₄ + FMAC groups, respectively, P <0.01). Histologic examinations showed that CCl₄ + FMAC subgroups had thinner or less fibrotic septa than CCl₄ group. RT-PCR analysis indicated that FMAC (1 g/kg) reduced mRNA levels of collagen I, TIMP-1 and TGF-β1 (collagen I: 5.63 ± 2.08 and 1.78 ± 0.48 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01; TIMP-1: 1.70 ± 0.82 and 0.34 ± 0.02 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01; TGF-β1:38.03 ± 11.9 and 4.26 ± 2.17 in CCl₄ and CCl₄ + FMAC groups, respectively, P < 0.01) in the CCl₄-treated liver.

CONCLUSION: It demonstrates that FMAC can retard the progression of liver fibrosis induced by CCl₄ in rats.

In vitro protective effects of salvianolic acid B on primary hepatocytes and hepatic stellate cells

The production of reactive oxygen species (ROS) is believed to be involved in liver injury and hepatic fibrosis. Activation of hepatic stellate cells (HSCs) is a key feature of liver fibrosis. Salvia miltiorrhiza is a traditional Chinese herb used in the treatment of cardiovascular and liver diseases to resolve stasis. The effects of salvianolic acid B (Sal B), a major component of Salvia miltiorrhiza, on oxidative damage include free radical DPPH scavenging, malondialdehyde (MDA) formation and ROS generation in primary rat hepatocytes and HSCs, and on alpha-SMA, and collagen expression in transforming growth factor-beta1 (TGF-beta1)-stimulated HSCs were examined. Results indicated that Sal B scavenged DPPH potently with an IC50 2.2+/-0.2 microg/ml (3.06+/-0.3 microM), inhibited lipid peroxidation and eliminated ROS accumulation in a concentration-dependent manner on primary rat hepatocytes and HSCs. Sal B also reduced alpha-SMA and collagen synthesis and deposition in HSCs, and had no direct cytotoxicity on both hepatocytes and HSCs. Our results suggest that Sal B ameliorated oxidative damage and eliminated ROS accumulation in hepatocytes, and attenuated HSC activation, potentially conferring hepatoprotective and anti-fibrogenic effects.

Anti-fibrotic effects of thalidomide on hepatic stellate cells and dimethylnitrosamine-intoxicated rats

Tumor necrosis factor-alpha (TNF-alpha) plays a central role in cellular necrosis, apoptosis, organ failure, tissue damage, inflammation and fibrosis. These processes, occurring in liver injury, may lead to cirrhosis. Thalidomide, alpha-N-phthalidoglutarimide, (C(13)H(10)N(2))(4), has been shown to have immunomodulatory and anti-inflammatory properties, possibly mediated through its anti-TNF-alpha effect. In this study, we investigated the in vitro and in vivo effects of thalidomide on hepatic fibrosis. A cell line of rat hepatic stellate cells (HSC-T6) was stimulated with transforming growth factor-beta1 (TGF-beta1) or TNF-alpha. The inhibitory effects of thalidomide on the NFkappaB signaling cascade and fibrosis markers including alpha-smooth muscle actin (alpha-SMA) and collagen, were assessed. An in vivo therapeutic study was conducted in dimethylnitrosamine (DMN)-treated rats, which were randomly assigned to 1 of 4 groups: vehicle (0.7% carboxyl methyl cellulose, CMC), thalidomide (40 mg/kg), thalidomide (200 mg/kg), or silymarin (50 mg/kg), each given by gavage twice daily for 3 weeks starting after 1 week of DMN administration. Thalidomide (100-800 nM) concentration-dependently inhibited NFkappaB transcriptional activity induced by TNF-alpha, including IKKalpha expression and IkappaBalpha phosphorylation in HSC-T6 cells. In addition, thalidomide also suppressed TGF-beta1-induced alpha-SMA expression and collagen deposition in HSC-T6 cells. Fibrosis scores of livers from DMN-treated rats receiving high dose of thalidomide (0.89 +/- 0.20) were significantly reduced in comparison with those of DMN-treated rats receiving vehicle (1.56 +/- 0.18). Hepatic collagen contents of DMN rats were also significantly reduced by either thalidomide or silymarin treatment. Immunohistochemical double staining results showed that alpha-SMA- and NFkappaB-positive cells were decreased in the livers from DMN rats receiving either thalidomide or silymarin treatment. In addition, real-time PCR analysis indicated that hepatic mRNA expressions of TGF-beta1, alpha-SMA, collagen 1alpha2, TNF-alpha and iNOS genes were attenuated by thalidomide treatment. In conclusion, our results showed that thalidomide inhibited activation of HSC-T6 cells by TNF-alpha and ameliorated liver fibrosis in DMN-intoxicated rats.

Effect of Chinese medicine Qinggan Huoxuefang on inducing HSC apoptosis in alcoholic liver fibrosis rats

AIM: To investigate the effect of Qinggan Huoxuefang (QGHXF) on improvement of liver function and pathology in rats, and to analyze the mechanism.

METHODS: Wistar rats were divided into three groups at random: normal control group (12),micro-amount carbon tetrachloride group (CCl₄)(12) and model group A (60). The model group A was ingested with the mixture (500 mL/L alcohol, 8 mL/kg per day; corn oil, 2 mL/kg per day; pyrazole, 24 mg/kg per day) once a day and intraperitoneal injections of 0.25 mL/kg of a 250 mL/L solution of CCl₄ in olive oil twice a week for 12 wk. The CCl₄ group received intraperitoneal injections only. At the end of 8 wk the model group A (60) was divided into 5 subgroups: model group, Xiaochaihu Chongji (XCH) group, QGHXF high dose group, moderate dose group and low dose group, and were given the drugs respectively. At the end of 12 wk, all the rats were killed and blood samples collected, as well as liver tissue. Blood samples were used for evaluation of alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyltransferase (γ-GT). Liver specimens were obtained for routine HE, apoptosis gene array and flow cytometry analysis.

RESULTS: A liver fibrosis animal model was successfully established. Fibrosis was obviously reduced in QGHXF high dose group, and no fibrosis formed in CCl₄ group. Compared with model group the QGHXF group and XCH group could obviously decrease the level of ALT, AST, ALP, and GGT (P  < 0.05). QGHXF high dose group was better than XCH group in ALT (615 ± 190 vs 867 ± 115), and AST(1972 ± 366 vs 2777 ± 608). Moreover, QGHXF could reduce liver inflammation, fibrosis-induced hepatic stellate cell (HSC) apoptosis and regulate apoptosis gene expression. The HSC apoptosis rates of QGHXF groups were 22.4 ± 3.13, 13.79 ± 2.26 and 10.07 ± 1.14, higher than model group, 6.58±1.04 (P  <  0.05). Compared to model group, 39 genes were up-regulated, 11 solely expressed and 17 down-regulated in high dose group.

CONCLUSION: QGHXF can improve liver fibrosis and induce HSC apoptosis.