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Fibrogenesis
Kinds of Fibrogenesis Selected AbstractsSignalling and regulation of collagen I synthesis by ET-1 and TGF-,1FEBS JOURNAL, Issue 24 2005Angelika Horstmeyer Endothelin-1 (ET-1) plays an important role in tissue remodelling and fibrogenesis by inducing synthesis of collagen I via protein kinase C (PKC). ET-1 signals are transduced by two receptor subtypes, the ETA- and ETB-receptors which activate different G, proteins. Here, we investigated the expression of both ET-receptor subtypes in human primary dermal fibroblasts and demonstrated that the ETA-receptor is the major ET-receptor subtype expressed. To determine further signalling intermediates, we inhibited G,i and three phospholipases. Pharmacologic inhibition of G,i, phosphatidylcholine-phospholipase C (PC-PLC) and phospholipase D (PLD), but not of phospholipase C,, abolished the increase in collagen I by ET-1. Inhibition of all phospholipases revealed similar effects on TGF-,1 induced collagen I synthesis, demonstrating involvement of PC-PLC and PLD in the signalling pathways elicited by ET-1 and TGF-,1. ET-1 and TGF-,1 each stimulated collagen I production and in an additive manner. ET-1 further induced connective tissue growth factor (CTGF), as did TGF-,1, however, to lower levels. While rapid and sustained CTGF induction was seen following TGF-,1 treatment, ET-1 increased CTGF in a biphasic manner with lower induction at 3 h and a delayed and higher induction after 5 days of permanent ET-1 treatment. Coincidentally at 5 days of permanent ET-1 stimulation, a switch in ET-receptor subtype expression to the ETB-receptor was observed. We conclude that the signalling pathways induced by ET-1 and TGF-,1 leading to augmented collagen I production by fibroblasts converge on a similar signalling pathway. Thereby, long-time stimulation by ET-1 resulted in a changed ET-receptor subtype ratio and in a biphasic CTGF induction. [source] Tumor necrosis factor,like weak inducer of apoptosis is a mitogen for liver progenitor cells,,HEPATOLOGY, Issue 1 2010Janina E. E. Tirnitz-Parker Liver progenitor cells (LPCs) represent the cell compartment facilitating hepatic regeneration during chronic injury while hepatocyte-mediated repair mechanisms are compromised. LPC proliferation is frequently observed in human chronic liver diseases such as hereditary hemochromatosis, fatty liver disease, and chronic hepatitis. In vivo studies have suggested that a tumor necrosis factor family member, tumor necrosis factor,like weak inducer of apoptosis (TWEAK), is promitotic for LPCs; whether it acts directly is not known. In our murine choline-deficient, ethionine-supplemented (CDE) model of chronic liver injury, TWEAK receptor [fibroblast growth factor-inducible 14 (Fn14)] expression in the whole liver is massively upregulated. We therefore set out to investigate whether TWEAK/Fn14 signaling promotes the regenerative response in CDE-induced chronic liver injury by mitotic stimulation of LPCs. Fn14 knockout (KO) mice showed significantly reduced LPC numbers and attenuated inflammation and cytokine production after 2 weeks of CDE feeding. The close association between LPC proliferation and activation of hepatic stellate cells in chronic liver injury prompted us to investigate whether fibrogenesis was also modulated in Fn14 KO animals. Collagen deposition and expression of key fibrogenesis mediators were reduced after 2 weeks of injury, and this correlated with LPC numbers. Furthermore, the injection of 2-week-CDE-treated wildtype animals with TWEAK led to increased proliferation of nonparenchymal pan cytokeratin,positive cells. Stimulation of an Fn14-positive LPC line with TWEAK led to nuclear factor kappa light chain enhancer of activated B cells (NF,B) activation and dose-dependent proliferation, which was diminished after targeting of the p50 NF,B subunit by RNA interference. Conclusion: TWEAK acts directly and stimulates LPC mitosis in an Fn14-dependent and NF,B-dependent fashion, and signaling via this pathway mediates the LPC response to CDE-induced injury and regeneration. (HEPATOLOGY 2010) [source] CCR2 promotes hepatic fibrosis in mice,HEPATOLOGY, Issue 1 2009Ekihiro Seki Chemokines and chemokine receptors contribute to the migration of hepatic stellate cells (HSCs) and Kupffer cells, two key cell types in fibrogenesis. Here, we investigate the role of CCR2, the receptor for monocyte chemoattractant protein (MCP)-1, MCP-2, and MCP-3, in hepatic fibrosis. Hepatic CCR2, MCP-1, MCP-2, and MCP-3 messenger RNA expression was increased after bile duct ligation (BDL). Both Kupffer cells and HSCs, but not hepatocytes, expressed CCR2. BDL- and CCl4 -induced fibrosis was markedly reduced in CCR2,/, mice as assessed through collagen deposition, ,-smooth muscle actin expression, and hepatic hydroxyproline content. We generated CCR2 chimeric mice by the combination of clodronate, irradiation, and bone marrow (BM) transplantation allowing full reconstitution of Kupffer cells, but not HSCs, with BM cells. Chimeric mice containing wild-type BM displayed increased macrophage recruitment, whereas chimeric mice containing CCR2,/, BM showed less macrophage recruitment at 5 days after BDL. Although CCR2 expressed in the BM enhanced macrophage recruitment in early phases of injury, CCR2 expression on resident liver cells including HSCs, but not on the BM, was required for fibrogenic responses in chronic fibrosis models. In vitro experiments demonstrated that HSCs deficient in CCR2,/, or its downstream mediator p47phox,/, did not display extracellular signal-regulated kinase and AKT phosphorylation, chemotaxis, or reactive oxygen species production in response to MCP-1, MCP-2, and MCP-3. Conclusion: Our results indicate that CCR2 promotes HSC chemotaxis and the development of hepatic fibrosis. (HEPATOLOGY 2009.) [source] Activation of hepatic stellate cells after phagocytosis of lymphocytes: A novel pathway of fibrogenesis,HEPATOLOGY, Issue 3 2008Nidal Muhanna Increased CD8-T lymphocytes and reduced natural killer (NK) cells contribute to hepatic fibrosis. We have characterized pathways regulating the interactions of human hepatic stellate cells (HSCs) with specific lymphocyte subsets in vivo and in vitro. Fluorescence-activated cell sorting (FACS) was used to characterize human peripheral blood lymphocytes (PBLs) and intrahepatic lymphocytes (IHLs) obtained from healthy controls and from patients with either hepatitis B virus (HBV) or hepatitis C virus (HCV) with advanced fibrosis. Liver sections were analyzed by immunohistochemistry and confocal microscopy. To investigate in vitro interactions, PBLs from healthy controls or patients with HCV cirrhosis were co-cultured with an immortalized human HSC line (LX2 cells) or with primary HSCs. Significant alterations in lymphocyte distribution were identified in IHLs but not PBLs. The hepatic CD4/CD8 ratio and NK cells were significantly reduced in HBV/HCV patients. Expression of alpha-smooth muscle actin and infiltration of CD4, CD8, and NK cells were readily apparent in liver sections from patients with cirrhosis but not in healthy controls. Lymphocytes from each subset were in proximity to HSCs primarily within the periportal regions, and some were directly attached or engulfed. In culture, HSC activation was stimulated by HCV-derived CD8-subsets but attenuated by NK cells. Confocal microscopy identified lymphocyte phagocytosis within HSCs that was completely prevented by blocking intracellular adhesion molecule 1 (ICAM-1) and integrin molecules, or by irradiation of HSCs. LX2 knockdown of either Cdc42 or Rac1 [members of the Rho-guanosine triphosphatase (GTPase) family] prevented both phagocytosis and the activation of HSC by HCV-derived lymphocytes. Conclusion: The CD4/CD8 ratio and NK cells are significantly decreased in livers with advanced human fibrosis. Moreover, disease-associated but not healthy lymphocytes are engulfed by cultured HSCs, which is mediated by the Rac1 and Cdc42 pathways. Ingestion of lymphocytes by HSCs in hepatic fibrosis is a novel and potentially important pathway regulating the impact of lymphocytes on the course of hepatic fibrosis. (HEPATOLOGY 2008.) [source] A yellow bullet against the drivers of hepatic fibrogenesis,HEPATOLOGY, Issue 2 2008Ralf Weiskirchen Ph.D. No abstract is available for this article. [source] Upregulation of the tumor suppressor gene menin in hepatocellular carcinomas and its significance in fibrogenesis,HEPATOLOGY, Issue 5 2006Pierre J. Zindy 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 ,2(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-,),dependent collagen ,2(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-, response. (HEPATOLOGY 2006;44:1296,1307.) [source] Leptin-mediated neovascularization is a prerequisite for progression of nonalcoholic steatohepatitis in rats,HEPATOLOGY, Issue 4 2006Mitsuteru Kitade Nonalcoholic steatohepatitis (NASH) may cause fibrosis, cirrhosis, and hepatocellular carcinoma (HCC); however, the exact mechanism of disease progression is not fully understood. Angiogenesis has been shown to play an important role in the progression of chronic liver disease. The aim of this study was to elucidate the role of angiogenesis in the development of liver fibrosis and hepatocarcinogenesis in NASH. Zucker rats, which naturally develop leptin receptor mutations, and their lean littermate rats were fed a choline-deficient, amino acid,defined diet. Both Zucker and littermate rats showed marked steatohepatitis and elevation of oxidative stress markers (e.g., thiobarbital acid reactive substances and 8-hydroxydeoxyguanosine). In sharp contrast, liver fibrosis, glutathione- S -transferase placental form (GST-P)-positive preneoplastic lesions, and HCC developed in littermate rats but not in Zucker rats. Hepatic neovascularization and the expression of vascular endothelial growth factor (VEGF), a potent angiogenic factor, only increased in littermate rats, almost in parallel with fibrogenesis and carcinogenesis. The CD31-immunopositive neovessels were mainly localized either along the fibrotic septa or in the GST-P,positive lesions. Our in vitro study revealed that leptin exerted a proangiogenic activity in the presence of VEGF. In conclusion, these results suggest that leptin-mediated neovascularization coordinated with VEGF plays an important role in the development of liver fibrosis and hepatocarcinogenesis in NASH. (HEPATOLOGY 2006;44:983,991.) [source] A dual reporter gene transgenic mouse demonstrates heterogeneity in hepatic fibrogenic cell populationsHEPATOLOGY, Issue 5 2004Scott T. Magness Activation of hepatic stellate cells (HSCs) and other resident mesenchymal cells into myofibroblasts expressing alpha smooth muscle actin (,SMA) and collagen I is a key event in liver fibrogenesis. However, the temporal expression profiles of ,SMA and collagen I genes in these cells is unknown. To address this question, we studied ,SMA and collagen ,1(I) transcriptional patterns in primary cultures of HSCs, and additionally, in an in vivo model of secondary biliary fibrosis using transgenic mice that express the Discomsoma sp. red fluorescent protein (RFP) and the enhanced green fluorescent protein (EGFP) reporter genes under direction of the mouse ,SMA and collagen ,1(I) promoter/enhancers, respectively. The ,SMA-RFP mice were crossed with collagen-EGFP mice to generate double transgenic mice. Reporter gene expression in cultured HSCs demonstrated that both transgenes were induced at day 3 with continued expression through day 14. Interestingly, ,SMA and collagen ,1(I) transgenes were not coexpressed in all cells. Flow cytometry analysis showed three different patterns of gene expression: ,SMA-RFP positive cells, collagen-EGFP positive cells, and cells expressing both transgenes. ,SMA-only and ,SMA/collagen expressing cells showed higher expression levels of synaptophysin, reelin, MMP13, TIMP1, and ICAM-1 compared to collagen-only expressing cells, as assessed by real-time PCR. Following bile duct ligation, ,SMA and collagen ,1(I) transgenes were differentially expressed by peribiliary, parenchymal and vascular fibrogenic cells. Peribiliary cells preferentially expressed collagen ,1(I), while parenchymal myofibroblasts expressed both ,SMA and collagen ,1(I). In conclusion, these data demonstrate heterogeneity of gene expression in myofibroblastic cells during active fibrogenesis. These reporter mice provide a useful tool to further characterize fibrogenic cell types and to evaluate antifibrotic drugs. (HEPATOLOGY 2004.) [source] Differential regulation of TGF-, signal in hepatic stellate cells between acute and chronic rat liver injuryHEPATOLOGY, Issue 1 2002Yoshiya Tahashi During chronic liver injury, transforming growth factor , (TGF-,) plays a prominent role in stimulating liver fibrogenesis by myofibroblast-like cells derived from hepatic stellate cells (HSCs). On the other hand, Smad 7 was recently shown to antagonize the TGF-,,induced activation of signal-transducing Smads (2 and 3). In this study, we investigated the regulatory mechanisms of the TGF-, signals in rat HSCs during acute liver injury and myofibroblasts (MFBs) during chronic liver injury, focusing on the roles of Smad 2 and antagonistic Smad 7. In acute liver injury, HSC-derived TGF-, increased plasminogen activator inhibitor type 1 (PAI-1) and ,2(I) procollagen (COL1A2) transcripts. Smad 2 in HSCs during liver injury and primary cultured HSCs were activated by an autocrine mechanism, because high levels of Smad 2 phosphorylation and induction of PAI-1 transcript by TGF-, were observed in HSCs. Thereafter, Smad 7 induced by TGF-, negatively regulated the Smad 2 action. These results indicated that endogenous TGF,,mediated Smad 7 in HSCs terminated the fibrotic signals mediated by signal-transducing Smads, and might be involved in the transient response to autocrine TGF-, signal after acute liver injury. By contrast, Smad 7 was not induced by the autocrine TGF-, signal, and constitutive Smad 2 activation was observed in MFBs throughout chronic liver injury, although Smad 7 could inhibit the TGF-, signal requiring Smad 2 phosphorylation by activated TGF-, receptor in cultured MFBs. This constitutive phosphorylation of Smad 2 by endogenous TGF-, under a low level of Smad 7 could be involved in the progression of liver fibrosis. [source] Adenosine reverses a preestablished CCl4 -induced micronodular cirrhosis through enhancing collagenolytic activity and stimulating hepatocyte cell proliferation in ratsHEPATOLOGY, Issue 4 2001Rolando Hernández-Muñoz Cirrhosis is one of the most common causes of mortality worldwide, because hepatic dysfunction constitutes a potentially lethal condition. Having demonstrated the hepatoprotective effect of adenosine against CCl4 -induced cirrhosis, the present study was aimed at assessing adenosine's effect on an already-established micronodular cirrhosis. Chronic administration of CCl4 (10 weeks) induced a cirrhotic state, characterized by increased liver fibronectin and collagen types I and III content, enhanced expression of ,-1 (I) collagen mRNA, portal hypertension, and liver dysfunction. After CCl4 discontinuation (5 weeks), increased persitance of ,-1 (I) collagen mRNA expression and deposition, enhanced proline incorporation into collagen and prolyl hydroxylase activity evidenced active fibrogenesis. Several weeks after CCl4 withdrawal, deposited collagen showed an enhanced type I/III ratio, which was associated with deficient collagenolytic activity in cirrhotic livers. Liver expression of some metalloproteinases (MMPs) and of tissue inhibitors of MMPs (TIMPs) also indicated decreased collagen breakdown in cirrhotic livers. Parameters indicative of oxidative stress (mainly protein oxidation) were persistently augmented. These events were coincident with diminished regenerative capacity of the cirrhotic liver. Intraperitoneal adenosine administration to CCl4 -induced cirrhotic rats blocked active fibrogenesis and increased the collagen degradation (most probably by decreasing liver TIMPs levels), normalizing collagen-type ratios. In addition, the nucleoside promoted an effective hepatocyte's proliferation in the cirrhotic liver and accelerated normalization of parameters indicative of liver function and oxidative stress. Thus, adenosine readily reversed an experimental cirrhosis through stimulating liver collagenolytic and proliferative capacities, as well as by accelerating functional recovery. [source] Studies of murine schistosomiasis reveal interleukin-13 blockade as a treatment for established and progressive liver fibrosisHEPATOLOGY, Issue 2 2001Monica G. Chiaramonte In several allergic, autoimmune, and infectious diseases, fibrosis is a major cause of morbidity and mortality. Here, using a model of infection-induced liver fibrosis, we show that interleukin (IL)-13 is required at all stages of Schistosomiasis mansoni infection to induce fibrosis. IL-4 production was preserved in IL-13,deficient mice, yet failed to significantly contribute to the fibrotic response in either acute or chronic infection. Significant fibrosis develops in all infected mice, although the magnitude of the response varies widely in inbred mice. C3H/HeN, BALB/c, and C57BL/6 mice develop high, intermediate, and low levels of fibrosis, respectively. Despite these differences, IL-13 antagonism resulted in a marked amelioration of fibrosis in all strains. The fibrotic mechanism in the high- and low-responder strains was unrelated to their tissue eosinophil or mast cell responses, but did correlate with their patterns of IL-13, IL-10, and interferon gamma (IFN-,) mRNA expression. Indeed, severe fibrosis correlated with a high IL-13 and low IFN-,/IL-10 mRNA response. Because fibrotic diseases are typically progressive disorders, an important issue was to determine whether IL-13 inactivation might be used to treat an established and ongoing fibrotic disease. Here, IL-13 antagonism was highly efficacious, even after fibrosis and the Th2 cytokine response were firmly established. These studies demonstrate the central role played by IL-13 in fibrogenesis and suggest that therapeutic approaches aimed at disrupting the IL-13 pathway will be highly effective at preventing fibrotic disease caused by chronic Th2-mediated inflammatory reactions. [source] Proteome analysis of rat hepatic stellate cellsHEPATOLOGY, Issue 2 2000Dan Bach Kristensen Proteome analysis was performed on cellular and secreted proteins of normal (quiescent) and activated rat hepatic stellate cells. The stellate cells were activated either in vitro by cultivating quiescent stellate cells for 9 days or in vivo by injecting rats with carbon tetrachloride for 8 weeks. A total of 43 proteins/polypeptides were identified, which altered their expression levels when the cells were activated in vivo and/or in vitro. Twenty-seven of them showed similar changes in vivo and in vitro, including up-regulated proteins such as calcyclin, calgizzarin, and galectin-1 as well as down-regulated proteins such as liver carboxylesterase 10 and serine protease inhibitor 3. Sixteen of them showed different expression levels between in vivo and in vitro activated stellate cells. These results were reproducibly obtained in 3 independent experiments. The up-regulation of calcyclin, calgizzarin, and galectin-1, as well as the down-regulation of liver carboxylesterase 10 were directly confirmed in fibrotic liver tissues. Northern blots confirmed up-regulation of the messenger RNAs (mRNAs) of calcyclin, calgizzarin, and galectin-1 in activated stellate cells, indicating that these changes were controlled at the mRNA level. In addition a list compiling over 150 stellate cell proteins is presented. The data presented here thus provide a significant new protein-level insight into the activation of hepatic stellate cells, a key event in liver fibrogenesis. [source] Matrix metalloproteinase inhibitor, CTS-1027, attenuates liver injury and fibrosis in the bile duct-ligated mouseHEPATOLOGY RESEARCH, Issue 8 2009Alisan Kahraman Aim:, Excessive matrix metalloproteinase (MMP) activity has been implicated in the pathogenesis of acute and chronic liver injury. CTS-1027 is an MMP inhibitor, which has previously been studied in humans as an anti-arthritic agent. Thus, our aim was to assess if CTS-1027 is hepato-protective and anti-fibrogenic during cholestatic liver injury. Methods:, C57/BL6 mice were subjected to bile duct ligation (BDL) for 14 days. Either CTS-1027 or vehicle was administered by gavage. Results:, BDL mice treated with CTS-1027 demonstrated a threefold reduction in hepatocyte apoptosis as assessed by the TUNEL assay or immunohistochemistry for caspase 3/7-positive cells as compared to vehicle-treated BDL animals (P < 0.01). A 70% reduction in bile infarcts, a histological indicator of liver injury, was also observed in CTS-1027-treated BDL animals. These differences could not be ascribed to differences in cholestasis as serum total bilirubin concentrations were nearly identical in the BDL groups of animals. Markers for stellate cell activation (,-smooth muscle actin) and hepatic fibrogenesis (collagen 1) were reduced in CTS-1027 versus vehicle-treated BDL animals (P < 0.05). Overall animal survival following 14 days of BDL was also improved in the group receiving the active drug (P < 0.05). Conclusion:, The BDL mouse, liver injury and hepatic fibrosis are attenuated by treatment with the MMP inhibitor CTS-1027. This drug warrants further evaluation as an anti-fibrogenic drug in hepatic injury. [source] Non-invasive markers for the prediction of fibrosis in chronic hepatitis C infectionHEPATOLOGY RESEARCH, Issue 8 2008Timothy Cross Liver fibrosis occurs as a result of chronic liver injury and is the hallmark of chronic liver disease. The final stage of progressive liver fibrosis is cirrhosis, which is implicated in portal hypertension, end-stage liver disease and hepatocellular carcinoma. Liver biopsy has historically been the gold standard test for the assessment of liver fibrosis for liver diseases such as viral hepatitis, autoimmune hepatitis and primary biliary cirrhosis. Improved serological tests have enhanced the diagnosis of these conditions and reduced the need for liver biopsy. Liver biopsy is unpopular among patients and clinicians. It is associated with morbidity and mortality, and in addition is subject to sampling error, inter- and intra-observer variability. There is therefore a need for non-invasive markers of liver fibrosis that are accurate, reliable, cheap and easy to use. The aim of this review is to examine the different non-invasive methods that can be used to estimate the severity of fibrosis. The methods evaluated include clinical examination, routine laboratory investigations, imaging tests, specialized tests of liver function and finally serum extra-cellular matrix markers of fibrosis. The review mainly focuses on fibrogenesis in the context of chronic hepatitis C infection. [source] Immunopathogenesis of hepatitis C virus infection and hepatic fibrosis: New insights into antifibrotic therapy in chronic hepatitis CHEPATOLOGY RESEARCH, Issue 8 2007Rosângela Teixeira Fibrosis and cirrhosis represent the consequences of a sustained wound-healing response to chronic liver injury of any cause. Chronic hepatitis C virus (HCV) has emerged as a leading cause of cirrhosis in the USA and throughout the world. HCV may induce fibrogenesis directly by hepatic stellate cell activation or indirectly by promoting oxidative stress and apoptosis of infected cells. The ultimate result of chronic HCV injury is the accumulation of extracellular matrix with high density type I collagen within the subendothelial space of Disse, culminating in cirrhosis with hepatocellular dysfunction. The treatment of hepatitis C with the combination of pegylated interferon and ribavirin is still both problematic and costly, has suboptimal efficacy, serious side effects and a high level of intolerance, and is contraindicated in many patients. Hence, new approaches have assumed greater importance, for which there is an urgent need. The sustained progress in understanding the pathophysiology of hepatic fibrosis in the past two decades has increased the possibility of developing drugs specifically targeting the fibrogenic process. Future efforts should identify genetic markers associated with fibrosis risk in order to tailor the treatment of HCV infection based on genetically regulated pathways of injury and/or fibrosis. Such advances will expand the arsenal to overcome liver fibrosis, particularly in patients with hepatic diseases who have limited treatment options, such as those patients with chronic hepatitis C who have a high risk of fibrosis progression and recurrent HCV disease after liver transplantation. [source] Serum bFGF and VEGF correlate respectively with bowel wall thickness and intramural blood flow in Crohn's diseaseINFLAMMATORY BOWEL DISEASES, Issue 5 2004Dr. Antonio Di Sabatino MD Abstract Serum levels of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF),two factors known to promote tissue repair, fibroblast proliferation, and angiogenesis,were measured in Crohn's disease patients and correlated with bowel wall thickness (BWT), measured by conventional grey scale ultrasonography, and with the ileal intramural vessel flow, measured by contrast-enhanced color Doppler imaging. Serum samples were obtained from 25 patients with active Crohn's disease and 22 healthy volunteers, all sex- and age-matched. Serum bFGF and VEGF levels were measured by ELISA assay. All the patients were examined with conventional transabdominal bowel sonography. Color Doppler of the intramural enteric vessels was then performed after the intravenous injection of Levovist, a galactose-based sonographic contrast agent. In Crohn's disease patients, serum bFGF and VEGF were significantly higher compared with healthy volunteers. A positive correlation between serum bFGF and BWT and between serum VEGF and color Doppler signal intensity was found. The raised serum bFGF levels in Crohn's disease patients with intestinal strictures compared with patients with other phenotypes (fistulizing, inflammatory), together with the correlation observed between serum bFGF and BWT, suggests a possible involvement of bFGF in the process of transmural fibrogenesis in Crohn's disease. The higher levels of VEGF in those patients with increased intramural blood flow suggests that VEGF may be considered a marker of angiogenesis in this condition. [source] Medical therapy for Crohn's disease stricturesINFLAMMATORY BOWEL DISEASES, Issue 1 2004Gert Van Assche MD Abstract Intestinal fibrostenosis is a frequent and debilitating complication of Crohn's disease (CD), not only resulting in small bowel obstruction, but eventually in repeated bowel resection and short bowel syndrome. Over one third of patients with CD have a clear stenosing disease phenotype, often in the absence of luminal inflammatory symptoms. Intestinal fibrosis is a consequence of chronic transmural inflammation in CD. As in other organs and tissues, phenotypic transformation and activation of resident mesenchymal cells, such as fibroblasts and smooth muscle cells, underlie fibrogenesis in the gut. The molecular mechanisms and growth factors involved in this process have not been identified. However, it is clear that inflammatory mediators may have effects on mesenchymal cells in the submucosa and the muscle layers that are profoundly different from their action on leukocytes or epithelial cells. Transforming growth factor-beta (TGF-,), for instance, has profound anti-inflammatory activity in the mucosa and probably serves to keep physiologic inflammation at bay, but at the same time it appears to be driving the process of fibrosis in the deeper layers of the gut. Tumor necrosis factor, on the other hand, has antifibrotic bioactivity and pharmacologic inhibition of this cytokine carries a theoretical risk of enhanced stricture formation. Endoscopic management of intestinal strictures with balloon dilation is an accepted strategy to prevent or postpone repeated surgery, but careful patient selection is of paramount importance to ensure favorable long-term outcomes. Specific medical therapy aimed at preventing or reversing intestinal fibrosis is not yet available, but candidate molecules are emerging from research in the liver and in other organs. [source] Molecular mechanisms of calorie restriction's protection against age-related sclerosisIUBMB LIFE, Issue 12 2006Elena Chiarpotto Abstract The current knowledge on the molecular mechanisms of the protective effect of calorie restriction (CR) against age-related fibrosclerosis is tentatively reviewed with specific reference to the role of oxidative stress in aging. The effects of oxidative stress are often mediated by its own final products. Of these, 4-hydroxy-2,3-nonenal (HNE) induces the expression and synthesis of transforming growth factor ,1 (TGF,1) and activates nuclear binding of transcription factor activator protein 1 (AP-1) thus stimulating fibrogenesis. Several studies have shown that, as well as extending mean and maximum life span in a variety of species, CR delays the onset and slows the progression of a variety of age-associated diseases, including diabetes, cardiovascular diseases and neoplasia. However, the anti-aging mechanisms of CR are still not clearly understood. Of the numerous hypotheses put forward, one that still remains popular is protection against the age-associated increase of oxidative stress and consequent cell damage. CR protects the rat aorta from the age-related increase of both oxidative damage and fibrosis; as regards the possible mechanism/s of CR's protection against fibrosclerosis, it is conceivable that, by decreasing oxidative stress, CR reduces HNE levels and consequently TGF,1 expression and collagen deposition, likely by down-regulating the activation of Jun-N terminal kinase and of AP-1. Through the modulation of reactive oxygen species and oxidative stress CR may also attenuate the age-associated increase in the inflammatory milieu, thus preserving vascular functional integrity by suppressing the age-associated increase in inflammatory enzyme activities and prostanoids. iubmb Life, 58: 695-702, 2006 [source] Inflammatory cytokines induce the transformation of human dermal microvascular endothelial cells into myofibroblasts: a potential role in skin fibrogenesisJOURNAL OF CUTANEOUS PATHOLOGY, Issue 2 2007V. Chaudhuri Background:, The myofibroblast plays a central role in wound contraction and in the pathology of fibrosis. The origin(s) of this important cell type in skin has not been firmly established. Methods:, Human epithelioid dermal microvascular endothelial cells (HDMEC) were isolated from foreskin tissue and maintained in cell culture. The transformation of epithelioid HDMEC into myofibroblasts (EMT) was induced by the inflammatory cytokines interleukin-1, (IL-1,) or tumour necrosis factor-, (TNF-,), and the transformed cells were characterized by electron microscopy, immunohistochemistry and quantitative RT-PCR. Results:, After short-term exposure to IL-1, or TNF-, (<3 days), EMT was reversible; after long-term exposure (>10 days), EMT was permanent. The transformed cells were identified as myofibroblasts by cytoplasmic microfilaments with dense bodies and attachment plaques, by the expression of ,-smooth muscle actin, type I collagen and calponin, and by quantitative RT-PCR gene expression of type I collagen and ,-smooth muscle actin. Conclusions:, Long-term exposure to TNF-, or IL-1, induced the permanent transformation of HDMEC into myofibroblasts in cell culture. A similar transformation following chronic inflammatory stimulation in vivo may explain one source of myofibroblasts in skin fibrogenesis. [source] Expression of intercellular adhesion molecule-1 in hepatic stellate cellsJOURNAL OF DIGESTIVE DISEASES, Issue 1 2000Lu Lungen OBJECTIVE: To explore the expression of intercellular adhesion molecule-1 (ICAM-1) in hepatic stellate cells (HSC). METHODS: Via in situ perfusion with proteinase and collagenase and density-gradient centrifugation with Nycodenz, HSC were isolated and cultured from the livers of both normal Wistar rats and the livers of rats treated with carbon tetrachloride. Expression of ICAM-1 in HSC was detected by an immunohistochemistry assay and reverse transcription,polymerase chain reaction (RT-PCR). RESULTS: No ICAM-1 was expressed in the freshly isolated HSC of normal rats, but ICAM-1 was found in primary cultures of HSC at day 10 and in secondary cultures of HSC at day 7. Additionally, the intensity of the expression increased over time. Expression of ICAM-1 was observed in freshly isolated HSC from the livers of rats treated with carbon tetrachloride. CONCLUSIONS: Expression of ICAM-1 is related to the activation of HSC, hepatic inflammation and hepatic fibrogenesis. [source] Inhibition of plasminogen activator inhibitor-1 expression by siRNA in rat hepatic stellate cellsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 12 2008Ping-Fang Hu Abstract Background and Aim:, The plasminogen activator/plasmin system is known to regulate the extracellular matrix turnover. The aim of this study was to detect the role of plasminogen activator inhibitor-1 (PAI-1) during liver fibrogenesis and investigate the functional effects of PAI-1 gene silencing in rat hepatic stellate cells (HSCs) using small interfering RNA (siRNA). Methods:, Hepatic fibrosis in rats was induced through serial subcutaneously injections of CCl4 and the expression of PAI-1 was detected by immunohistochemistry and reverse transcription,polymerase chain reaction (PCR). PAI-1 siRNA molecules were constructed and transiently transfected into HSC-T6 using the cell suspension transfection method. The pSUPER RNA interfering system was used to establish the HSC stable cell line pSUPER-shPAI. Expression of alpha-smooth muscle actin, transforming growth factor-beta, tissue inhibitor of metalloproteinases-1, and collagen types I and III were evaluated by real-time PCR. Cell proliferation and the cell cycle were determined by the methyl thiazolyl tetrazolium (MTT) method and flow cytometry. Collagen content in HSCs supernatant was evaluated by enzyme-linked immunosorbent assay. Results:, The results showed that PAI-1 was upregulated during liver fibrosis, and its expression was closely correlated with the deposition of collagens. SiRNA molecules were successfully transfected into HSCs and induced inhibition of PAI-1 expression time dependently. Moreover, PAI-1 siRNA treatment downregulated alpha-smooth muscle actin, transforming growth factor-beta, tissue inhibitor of metalloproteinases-1 expression, and inhibited collagen types I and III synthesis both at the mRNA and protein level in transiently and stably transfected HSCs. Conclusions:, This study suggests a significant functional role for PAI-1 in the development of liver fibrosis and that downregulating PAI-1 expression might present as a potential strategy to treat liver fibrosis. [source] Molecular mechanisms of pancreatitis: Current opinionJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 9 2008Alain Vonlaufen Abstract Pancreatitis (necroinflammation of the pancreas) has both acute and chronic manifestations. Gallstones are the major cause of acute pancreatitis, whereas alcohol is associated with acute as well as chronic forms of the disease. Cases of true idiopathic pancreatitis are steadily diminishing as more genetic causes of the disease are discovered. The pathogenesis of acute pancreatitis has been extensively investigated over the past four decades; the general current consensus is that the injury is initiated within pancreatic acinar cells subsequent to premature intracellular activation of digestive enzymes. Repeated attacks of acute pancreatitis have the potential to evolve into chronic disease characterized by fibrosis and loss of pancreatic function. Our knowledge of the process of scarring has advanced considerably with the isolation and study of pancreatic stellate cells, now established as the key cells in pancreatic fibrogenesis. The present review summarizes recent developments in the field particularly with respect to the progress made in unraveling the molecular mechanisms of acute and chronic pancreatic injury secondary to gallstones, alcohol and genetic factors. It is anticipated that continued research in the area will lead to the identification and characterization of molecular pathways that may be therapeutically targeted to prevent/inhibit the initiation and progression of the disease. [source] Changing the pathogenetic roadmap of liver fibrosis?JOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 7pt1 2008Where did it start; where will it go? Abstract The pathophysiology of liver injury has attracted the interest of experimentalists and clinicians over many centuries. With the discovery of liver-specific pericytes , formerly called fat-storing cells, Ito-cells, lipocytes, and currently designated as hepatic stellate cells (HSC) , the insight into the cellular and molecular pathobiology of liver fibrosis has evolved and the pivotal role of HSC as a precursor cell-type for extracellular matrix,producing myofibroblasts has been established. Although activation and transdifferentiation of HSC to myofibroblasts is still regarded as the pathogenetic key mechanism of fibrogenesis, recent studies point to a prominent heterogeneity of the origin of myofibroblasts. Currently, the generation of matrix-synthesizing fibroblasts by epithelial,mesenchymal transition, by influx of bone marrow,derived fibrocytes into damaged liver tissue, and by differentiation of circulating monocytes to fibroblasts after homing in the injured liver are discussed as important complementary mechanisms to enlarge the pool of (myo-)fibroblasts in the fibrosing liver. Among the molecular mediators, transforming growth factor-beta (TGF-,) plays a central role, which is controlled by the bone-morphogenetic protein (BMP)-7, an important antagonist of TGF-, action. The newly discovered pathways supplement the linear concept of HSC activation to myofibroblasts, point to fibrosis as a systemic response involving extrahepatic organs and reactions, add further evidence to a more or less uniform concept of organ fibrosis in general (e.g. liver, lung, kidney), and offer innovative approaches for the development of non-invasive biomarkers and antifibrotic trials. [source] Effect of losartan on early liver fibrosis development in a rat model of nonalcoholic steatohepatitisJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 6 2007Patricio Ibañez Abstract Background and Aim:, Nonalcoholic steatohepatitis (NASH) is a metabolic disorder of the liver that may evolve into fibrosis or cirrhosis. Recent studies have shown reduction of experimental liver fibrosis with the use of angiotensin-converting-enzyme inhibitors or angiotensin-receptor antagonists. The aim of this study was to determine whether losartan can influence the early phase of fibrogenesis in an animal model of NASH. Methods:, To induce NASH, a choline-deficient diet (CDD) was given to Sprague-Dawley rats for 12 weeks. These animals were then compared with a control group receiving choline-supplemented diet (CSD) and a group fed a CDD plus losartan (10 mg/kg/day). Biochemical (serum levels of alanine aminotransferase and aspartate aminotransferase) and histological evaluation of fatty liver was performed by conventional techniques. Hydroxyproline content in liver tissue was assayed by spectrophotometry. In addition, mRNA levels of procollagen I and transforming growth factor (TGF)-, were assessed by semiquantitative RT-PCR and stellate cell activation by ,-actin immunofluorescence stain. Results:, After 12 weeks CDD induced a marked elevation of serum aminotranferases, a severe fatty liver infiltration with mild histological inflammation and fibrosis. These findings correlated with a significant increase in mRNA levels of both procollagen I and TGF-, and significant increased liver hydroxyproline content. No differences were seen between rats receiving CDD alone and rats receiving CDD plus losartan with regard to the biochemical, morphological or molecular alterations induced by the CDD. Conclusion:, Losartan does not seem to influence liver injury and fibrogenic events in the CDD model of NASH. [source] Genotype-specific mechanisms for hepatic steatosis in chronic hepatitis C infectionJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 8 2002Jason M Hui Abstract Background: Hepatic steatosis is common in hepatitis C, but the relative importance of host and viral factors is controversial. In the present prospective study, we examined metabolic factors associated with non-alcoholic fatty liver and viral genotype as predictors of steatosis and fibrosis in chronic hepatitis C infection. Methods: In 124 chronic hepatitis C patients, the association between liver histology and the following was investigated: demographic and anthropometric data, alcohol intake, alanine aminotransferase (ALT), total cholesterol, low-density lipoprotein,cholesterol, high-density lipoprotein,cholesterol, triglyceride, transferrin saturation, ferritin, insulin, c-peptide, glucose and insulin resistance (homeostasis model). Results: By multivariate analysis, genotype 3 was associated with increased steatosis grade (P = 0.02). There were significant pairwise interactions between genotype 3 status and total cholesterol (P = 0.01), current alcohol intake (P = 0.04) and serum ALT (P = 0.01). This showed that the etiology of steatosis was different in patients with genotype 3 and those with non-genotype 3 chronic hepatitis C infection. In genotype 3 patients, the degree of steatosis was inversely associated with serum cholesterol (P = 0.005) and positively associated with serum triglyceride (P = 0.02). There was no association between body mass index (BMI) and the extent of steatosis. Among patients with other genotypes, the steatosis grade was strongly influenced by BMI (P < 0.0001) and serum ALT (P < 0.01). Independent predictors of fibrosis were age (P = 0.001), past alcohol intake (P = 0.04), ALT (P = 0.002), serum insulin (P = 0.001) and portal inflammation (P < 0.001). Conclusions: Hepatitis C genotype 3 may interfere with pathways of hepatic lipid metabolism, whereas increased BMI appears to be a more important pathogenic factor in other genotypes. Although steatosis and BMI were not associated with hepatic fibrosis, their relationship with serum insulin suggests that metabolic factors related to insulin action could influence fibrogenesis in hepatitis C. [source] Serum amino-terminal propeptide of type III procollagen and 7S domain of type IV collagen correlate with hepatic iron concentration in patients with chronic hepatitis C following ,-interferon therapyJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 2 2001Ichiro Shimizu Abstract Background: It has been reported that chronic infection with hepatitis C virus is associated with excess iron deposits in the liver of subjects who are neither alcoholics nor recipients of blood transfusions. However, little is known about the relationship between hepatic iron concentration (HIC) and the serum levels of hepatic fibrogenesis markers, which were caused by interferon therapy for chronic hepatitis C. Therefore, changes in the serum amino-terminal propeptide of type III procollagen (P-III-P) and the 7S domain of type IV collagen (7S-IV) in 16 patients treated with ,-interferon (IFN-,) were studied, and their HIC and histological assessment evaluated. Hepatic iron concentrations were measured by using liver biopsy specimens obtained before and 6 months after the cessation of treatment. Methods and Results: Eight subjects (50%) who had normal alanine transaminase levels at 6 months after therapy showed significantly lowered HIC, and attenuated hepatic iron staining with decreased serum levels of P-III-P and 7S-IV compared to the remaining subjects. The HIC was significantly correlated with the serum levels of P-III-P and 7S-IV in all subjects. Conclusions: These findings suggest that IFN-, treatment may decrease stimuli for fibrogenesis, at least in part, by reducing the hepatic iron deposition in patients with chronic hepatitis C. [source] Biochemical markers of hepatic fibrogenesis: Single measurements are not reliable enough to replace liver biopsyJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 8 2000Jacob George No abstract is available for this article. [source] Treatment of chronic liver diseases with traditional Chinese medicineJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 2000Bao-En Wang Traditional Chinese medicine is still being extensively used for treatment of liver disease in China. The anti-viral herbs, Phyllanthus amarus, P. niruri and P. urninaria, and Oxymatrine extracted from Sophora flavecientis and S. subprostratae, have been shown to have a remarkable HBV suppressing effect with a serum conversion rate for HBeAg and HBV DNA around 45%, similar to that of IFN-,. The anti-inflammatory compound, Stronger NeoMinophagen C (SNMC), is a Japanese preparation of glycerrhizin, extracted from Glyceriza glabra, which has shown an effective rate of ALT and AST normalization and reduction to < 60 U/L in 65.6% and 73.5% of patients. Compound 861, made of 10 herbs with Salvia miltiorrhiza as its chief component, has been shown experimentally to be effective in suppressing fibrogenesis, enhancing collagen degradation, and inhibiting TIMP expression. Clinically, an open trial of 2000 patients showed improvement of symptoms in 83% and normalization of serum ALT in 82%. In a controlled study of 107 patients with HBV-related diseases, double liver biopsies showed that the fibrosis reversal rate after 6 months treatment with Cpd 861 was 78% in S2, 82% in S3 (precirrhotic stage) and 75% in S4 (early cirrhosis), as assessed by Scheuer's and Chevallier's criterion. In conclusion, traditional Chinese medicine has great potential in the treatment of chronic hepatitis B. [source] Long-term administration of Salvia miltiorrhiza ameliorates carbon tetrachloride-induced hepatic fibrosis in ratsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2003Tzung-Yan Lee ABSTRACT Carbon tetrachloride (CCl4) is metabolized by cytochrome P450 to form a reactive trichloromethyl radical that triggers a chain of lipid peroxidation. These changes lead to cell injury, and chronic liver injury leads to excessive deposition of collagen in liver, resulting in liver fibrosis. The aim of this study was to evaluate the effects of long-term Salvia miltiorrhiza administration in CCl4 -induced hepatic injury in rats. Salvia miltiorrhiza (10, 25 or 50 mg kg,1 twice a day) was given for 9 weeks, beginning at the same time as the injections of CCl4. Rats receiving CCl4 alone showed a decreased hepatic glutathione level and an increased glutathione-S-transferase content. The hepatic thiobarbituratic acid-reactive substance levels were increased. CCl4 also caused a prominent collagen deposition in liver histology that was further supported by the increased hepatic mRNA expression of transforming growth factor-,1, tissue inhibitor of metallproteinase-1 and procollagen I. Salvia miltiorrhiza administration led to a dose-dependent increase in hepatic glutathione levels and a decrease in peroxidation products. Additionally, it reduced the mRNA expression of markers for hepatic fibrogenesis. In conclusion, long-term administration of Salvia miltiorrhiza in rats ameliorated the CCl4 -induced hepatic injury that probably related to a reduced oxidant stress and degree of hepatic fibrosis. [source] Alcohol, Signaling, and ECM TurnoverALCOHOLISM, Issue 1 2010Devanshi Seth Alcohol is recognized as a direct hepatotoxin, but the precise molecular pathways that are important for the initiation and progression of alcohol-induced tissue injury are not completely understood. The current understanding of alcohol toxicity to organs suggests that alcohol initiates injury by generation of oxidative and nonoxidative ethanol metabolites and via translocation of gut-derived endotoxin. These processes lead to cellular injury and stimulation of the inflammatory responses mediated through a variety of molecules. With continuing alcohol abuse, the injury progresses through impairment of tissue regeneration and extracellular matrix (ECM) turnover, leading to fibrogenesis and cirrhosis. Several cell types are involved in this process, the predominant being stellate cells, macrophages, and parenchymal cells. In response to alcohol, growth factors and cytokines activate many signaling cascades that regulate fibrogenesis. This mini-review brings together research focusing on the underlying mechanisms of alcohol-mediated injury in a number of organs. It highlights the various processes and molecules that are likely involved in inflammation, immune modulation, susceptibility to infection, ECM turnover and fibrogenesis in the liver, pancreas, and lung triggered by alcohol abuse. [source] | ||||||||||||||||||||||||||||||||||