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Background & Aims: Accumulating evidence indicates that acetaldehyde (AcCHO) is one of the main mediators of fibrogenesis in alcoholic liver disease. AcCHO stimulates synthesis of fibrillar collagens in hepatic stellate cells, but the molecular events directly involved in the activation of collagen genes are debatable. Methods: Peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that is expressed in stellate cells, and its activation by specific ligands inhibits collagen synthesis. In this study, we evaluated the effects of AcCHO on PPARγ transcriptional activity and its correlation with the AcCHO-induced collagen synthesis in hepatic stellate cells. Results: AcCHO treatment inhibited ligand-dependent and -independent PPARγ transcriptional activity, and this effect was correlated with an increased phosphorylation of a mitogen-activated protein kinase site at serine 84 of the human PPARγ. Transfection of the PPARγSer84Ala mutant completely prevented the effect of AcCHO on PPARγ activity and in parallel abrogated the induction of collagen gene expression by AcCHO. The effect of AcCHO on PPARγ activity and phosphorylation was blocked by extracellular signal–regulated kinase (ERK) 1/2 and protein kinase C (PKC)δ inhibitors as well as by catalase, suggesting that hydrogen peroxide is involved in the molecular cascade responsible for PPARγ phosphorylation via activation of the PKCδ/ERK pathway. Furthermore, inhibition of c-Abl completely abrogated the effect of AcCHO on either PPARγ function or collagen synthesis; in addition, expression of the PPARγSer84Ala mutant prevented the profibrogenic signals mediated by c-Abl activation. Conclusions: Our results showed that the induction of collagen expression by AcCHO in stellate cells is dependent on PPARγ phosphorylation induced by a hydrogen peroxide–mediated activation of the profibrogenic c-Abl signaling pathway.

Background & aims: The chemokines CCL19 and CCL21 bind CCR7, which is involved in the organization of secondary lymphoid tissue and is expressed during chronic tissue inflammation. We investigated the expression of CCL21 and CCR7 in chronic hepatitis C. The effects of CCL21 on hepatic stellate cells (HSCs) were also studied. Methods: Expression of CCL21 was assessed by in situ hybridization and immunohistochemistry. CCR7 on T cells was analyzed by flow cytometry. Cultured human HSCs were studied in their activated phenotype. Results: In patients with chronic hepatitis C, expression of CCL21 and CCR7 was up-regulated. CCL21 was detected in the portal tracts and around inflammatory lymphoid follicles, in proximity to T lymphocytes and dendritic cells, which contributed to expression of this chemokine. Expression of CCR7 was also increased in patients with primary biliary cirrhosis. Intrahepatic CD8 + T lymphocytes isolated from patients with chronic hepatitis C had a significantly higher percentage of positivity for CCR7 than those from healthy controls, and the expression of CCR7 was associated with that of CXCR3. Cultured HSCs expressed functional CCR7, the activation of which stimulated cell migration and accelerated wound healing in an in vitro model. Exposure of HSCs to CCL21 triggered several signaling pathways, including extracellular signal-regulated kinase, Akt, and nuclear factor κB, resulting in induction of proinflammatory genes. Conclusions: Expression of CCL21 during chronic hepatitis C is implicated in the recruitment of T lymphocytes and the organization of inflammatory lymphoid tissue and may promote fibrogenesis in the inflamed areas via activation of CCR7 on HSCs.

Background: Fat storing cells (FSC) are nonparenchymal liver cells generally considered the major source of the hepatic extracellular matrix (ECM). Transforming growth factor β 1 (TGF- β 1 ) is a potent regulator of ECM synthesis in various cell types. In this study, the effect of TGF- β 1 on procollagen types I, III, IV, laminin (Lam), and flbronectin (FN) synthesis in cultured human FSCs was analyzed. Methods: FSCs were isolated from wedge sections of normal human livers. Morphological studies were performed by immunofluorescence and electron microscopy. ECM components in human FSC cultures were measured by an enzyme-linked immunosorbent assay. The expression of messenger RNA (mRNA) was evaluated by Northern blot and in situ hybridization. Results: Cultured human FSCs displayed numerous fat droplets in the perinuclear zone, and immunoreactivity for vimentin and α-smooth muscle actin. A weak nonfibrillar staining was observed by using a polyclonal antidesmin antibody. TGF- β 1 induced a dose-dependent increase of procollagen I, III, and FN accumulation in human FSC cultures, whereas procollagen IV and Lam production was not affected. Furthermore, TGF- β 1 increased the expression of α 1 (I), α 1 (III) procollagen, FN and TGF- β 1 mRNA in human FSC cultures. Conclusions: These data indicate that TGF- β 1 is able to increase the synthesis of procollagen I, III, and FN in cultured human FSCs. Moreover, TGF- β 1 can induce its own mRNA in the same cells.

Background & Aims: Inadequate data are available about retreatment of nonresponders to interferon (IFN) and ribavirin. Thus, this study evaluated the efficacy and tolerability of a 48-week therapy with pegylated IFN-α-2b plus high-dose ribavirin in patients who have failed to respond to the combination. Treatment up to 48 weeks also in patients who have failed to clear hepatitis C virus (HCV) RNA by week 24 was also evaluated. Methods: One hundred forty-one patients who previously did not respond to IFN and ribavirin, 86% with genotype 1 or 4 infection, 52% with high viral load (>800.000 IU/mL), 22% with cirrhosis, were retreated with pegylated IFN-α-2b 1.5 μg/kg per week and ribavirin 1000–1200 mg/day for 48 weeks and followed up for 24 weeks. Results: By intent-to-treat analysis, 20% of patients achieved a sustained virologic response (SVR). SVR of genotype 1 patients was 19%. Independent predictors of SVR were low γ-glutamyltransferase levels (OR, 22.9; 95% CI: 6.6–79.6) and low viral load (OR, 3.8; 95% CI: 1.1–12.6). Twelve (23%) out of 51 patients who were HCV RNA positive after 24 weeks of therapy achieved a late virologic response (after week 24) and 5 (10%) of them, all with genotype 1, achieved an SVR. Genotype was not associated with response ( P = .2) or with early response ( P = .3). Conclusions: Retreatment with pegylated IFN-α-2b and ribavirin of multiexperienced and "difficult to treat" nonresponder patients produced a very promising SVR. Accurate selection of patients, such as those with low viral load and low γ-glutamyltransferase levels, and prolongation of therapy beyond 24 weeks also in HCV RNA-positive patients may further increase the rate of SVR.

The chemokines CCL19 and CCL21 bind CCR7, which is involved in the organization of secondary lymphoid tissue and is expressed during chronic tissue inflammation. We investigated the expression of CCL21 and CCR7 in chronic hepatitis C. The effects of CCL21 on hepatic stellate cells (HSCs) were also studied.Expression of CCL21 was assessed by in situ hybridization and immunohistochemistry. CCR7 on T cells was analyzed by flow cytometry. Cultured human HSCs were studied in their activated phenotype.In patients with chronic hepatitis C, expression of CCL21 and CCR7 was up-regulated. CCL21 was detected in the portal tracts and around inflammatory lymphoid follicles, in proximity to T lymphocytes and dendritic cells, which contributed to expression of this chemokine. Expression of CCR7 was also increased in patients with primary biliary cirrhosis. Intrahepatic CD8(+) T lymphocytes isolated from patients with chronic hepatitis C had a significantly higher percentage of positivity for CCR7 than those from healthy controls, and the expression of CCR7 was associated with that of CXCR3. Cultured HSCs expressed functional CCR7, the activation of which stimulated cell migration and accelerated wound healing in an in vitro model. Exposure of HSCs to CCL21 triggered several signaling pathways, including extracellular signal-regulated kinase, Akt, and nuclear factor kappaB, resulting in induction of proinflammatory genes.Expression of CCL21 during chronic hepatitis C is implicated in the recruitment of T lymphocytes and the organization of inflammatory lymphoid tissue and may promote fibrogenesis in the inflamed areas via activation of CCR7 on HSCs.

BACKGROUND & AIMS: Endothelin (ET) 1 could be involved in the regulation of hepatic microcirculation and in the development of portal hypertension. The expression and distribution of ET-1 in normal and cirrhotic liver tissue and its effects on hepatic stellate cells (HSCs), liver-specific pericytes, were investigated. METHODS: ET-1 expression in liver tissue was analyzed using in situ hybridization and immunohistochemistry. Secretion of ET-1 by HSC was evaluated by radioimmunoassay. Changes in intracellular Ca2+ concentration and cell contraction were studied using digital video imaging. Specific binding of ET-1 was evaluated using self- and cross-displacement curves. RESULTS: ET-1 expression was markedly enhanced in cirrhotic liver tissue, where activated HSCs were shown to be major sites of ET-1 synthesis, as confirmed by studies performed on cultured human HSC. ET- 1 exerted several biological actions on HSC, including mitogenicity, activation of mitogen-activated protein kinase, and a rapid increase in intracellular Ca2+ coupled with reversible cell contraction. All these effects appeared to be mediated by ETA receptors. Finally, the relative prevalence of ETA and ETB binding sites changed with the progressive phenotypical modulation of HSC. CONCLUSIONS: ET-1 may act as a paracrine and autocrine factor for activated HSC and contribute to the increased resistance to portal flow in cirrhotic liver. (Gastroenterology 1996 Feb;110(2):534-48)

Background/Aims: The molecular defect of genetic hemochromatosis (GH) is unknown. It is believed that low expression of duodenal ferritin in GH is caused by tissue or cell specific defect of ferritin synthesis. Our study was designed to ascertain whether the control of duodenal ferritin synthesis in GH was defective. Methods: Expression at the single cell level of H and L ferritin messenger RNAs and protein and activity of the iron regulatory factor, which controls the translation of ferritin messenger RNA, were assessed in 43 duodenal biopsy specimens from individuals with GH, secondary hemochromatosis (SH), anemia, or normal iron balance. Results: Signal for ferritin H and L subunit messenger RNAs was detected in both absorptive and nonabsorptive cells by in situ hybridization, but in 10 of 14 patients with untreated GH, the signal was lower than in patients with SH or normal subjects. However, immunostaining for ferritin protein documented a diffuse/cytoplasmic pattern, whereas a supranuclear/granular staining was found in normal subjects or patients with SH. The spontaneous activity of duodenal iron regulatory factor was consistently higher in patients with GH than in normal subjects or subjects with anemia or SH. Conclusions: In patients with GH, ferritin gene transcription is preserved in both absorptive and nonabsorptive intestinal cells. Low accumulation of ferritin is not caused by a defective control of ferritin synthesis but by low expression of ferritin messenger RNA and sustained activity of iron regulatory factor.

A S L D A b st ra ct s levels were significantly decreased in UDCA group compared to control group. Microarray analysis revealed that gene expression of glutathione S-transferase (GST) ismarkedly increased in UDCA group compared to control group. Since Nrf2-activated genes such as glutamatecysteine ligase, catalytic subunit (Gclc), heme oxygenase 1 (HO-1) exert antioxidant effects, we next investigated mRNA expression levels of these genes by quantitative real-time PCR. Quantitative real-time PCR revealed the elevated expression of both Gclc and HO-1 in UDCA group. Conclusion : UDCA administration blocks progression of liver inflammation in NASH by inducing Nrf2-regulated antioxidant gene expression and reducing serum ROS levels.

The cellular localization of procollagen types I, III, IV, and V gene transcripts was determined in tissues from 12 patients with either Crohn's disease (CD) or ulcerative colitis (UC) and nine controls by in situ hybridization with 35S-labeled RNA probes. In CD, the signal intensity and number of labeled cells were significantly increased, particularly in deeper intestinal layers. In contrast, the labeled cells in UC were concentrated in the subepithelial intestinal layers, with an overexpression of procollagen III RNA transcripts. Immunohistological stainings for procollagen types I, III, and IV showed a weaker staining in UC than in CD, indicating that increased transcript levels in UC are unrelated to the enhanced collagen protein deposition, although the increase of procollagen messenger RNA levels correlated with the density of the inflammatory infiltrate. It was concluded that both CD and UC show highly increased procollagen RNA transcript levels but differ in collagen deposition. Thus, different posttranscriptional or posttranslational regulatory mechanisms, such as collagen degradation, may account for the observed differences.

To localize the cellular sources of the collagens excessively deposited in the liver in the course of secondary biliary fibrosis, we have analyzed by in situ hybridization the distribution of alpha 2(I), alpha 1(III), and alpha 1(IV) procollagen and albumin RNA transcripts in rat livers up to 6 wk following common bile duct ligation and scission. In normal liver, moderate amounts of alpha 2(I) and alpha 1(III) procollagen RNA were found in nonparenchymal cells, while alpha 1(IV) procollagen gene expression was at the threshold of detection. Following bile duct obstruction, increasing amounts of alpha 2(I), alpha 1(III), and alpha 1(IV) procollagen gene transcripts were observed in cells of the expanding portal tracts and in perisinusoidal cells in areas of excessive collagen deposition. Procollagen gene expressing perisinusoidal cells were colocalized with desmin-immunoreactive cells, suggesting that Ito cells and transitional cells were among the collagen-expressing cell types. Only alpha 1(IV) procollagen transcripts were found in epithelial cells of newly formed bile ducts. Neither normal nor fibrotic liver showed any hybridization signal above background over hepatocytes, indicating that hepatocytes are unlikely to be a major source of hepatic collagen.