Muscle Actin-positive Hepatic Stellate Cells Research Articles

Immunohistochemical Study of Stellate Cells in Patients with Chronic Viral Heptitis C Histopathological study

Background: Chronic hepatitis is defined as liver inflammation that lasts for at least 6 months. The Hepatitis C virus is responsible for 60 to 70% of chronic hepatitis cases; the virus causes continued inflammation that slowly damages the liver, eventually leading to cirrhosis, liver failure, and, in rare cases, liver cancer. Aim of the work: To evaluate the changes in distribution and percentage of alpha-smooth muscle actin-positive hepatic stellate cells and the correlation with the degree of the fibrosis in cirrhotic livers, in patients with HCV chronic hepatitis. Material and methods: 50 hepatic core biopsies selected randomly were received from Histopathology Department at National Hepatology and Tropical Medicine Research Institute and examined for histopathological features using (hematoxylin and eosin), stage of hepatic fibrosis using stellate cell Masson s' trichrome stain, and examined for stellate cell activity using alpha smooth muscle actin (ASMA) immunostaining. Results: The relation between degree of ASMA expression by stellate cells and stage of fibrosis was highly significant with a p value <0.001, also the relation between degree of necroinflammation and degree of ASMA expression by stellate cells was highly significant with a p value <0.001. The relation between degree of necroinflammation and stage of fibrosis was highly significant with a p value <0.001. The relation between age of patient and stage of fibrosis also was statistically significant with a p value =0.012. The relation between age of patient and degree of necroinflammation was statistically significant with a p value =0.017. Conclusion: To summarize from hepatic core biopsies of patients suffering from chronic HCV, the number of active stellate cells was found to be positively associated with stage of hepatic fibrosis.

Human Amnion-Derived Mesenchymal Stem Cell Transplantation Ameliorates Liver Fibrosis in Rats.

Mesenchymal stem cells (MSCs) are a valuable cell source in regenerative medicine. Recently, several studies have shown that MSCs can be easily isolated from human amnion. In this study, we investigated the therapeutic effect of transplantation of human amnion-derived MSCs (hAMSCs) in rats with liver fibrosis. Liver fibrosis was induced by an intraperitoneal injection of 2 mL/kg of 50% carbon tetrachloride twice a week for 6 weeks. At 3 weeks, hAMSCs (1 × 10(6) cells) were transplanted intravenously. Rats were sacrificed at 7 weeks, and histological analyses and quantitative reverse-transcription polymerase chain reaction were performed. In vitro experiments were conducted to investigate the effect of hAMSCs on the activation of Kupffer cells. Transplantation of hAMSCs significantly reduced the fibrotic area, deposition of type-I collagen, the number of α-smooth muscle actin-positive hepatic stellate cells, and CD68-positive Kupffer cells in the livers. messenger RNA expression of α-smooth muscle actin and tissue inhibitor of metalloproteinase-1 was significantly decreased and the expression of matrix metalloproteinase-9 and hepatocyte growth factor was significantly increased in the liver of hAMSC-treated rats. Transplantation of hAMSCs at 3 weeks plus 5 weeks did not have an additive effect. In vitro experiments demonstrated that Kupffer cell activation induced by lipopolysaccharide was significantly decreased by culturing with conditioned medium obtained from hAMSCs. Transplantation of hAMSCs provided significant improvement in a rat model of liver fibrosis, possibly through the inhibition of Kupffer cell and hepatic stellate cell activation. hAMSCs may be a potential new treatment for liver fibrosis.

Transgenic expression of human neutrophil peptide‐1 enhances hepatic fibrosis in mice fed a choline‐deficient, L‐amino acid–defined diet

Neutrophils infiltrate the livers of patients with nonalcoholic steatohepatitis (NASH). Human neutrophil peptides (HNPs) induce cytokine and chemokine production under inflammatory conditions, which may contribute to the progression of NASH. In this study, we focused on the effects of HNP-1 on hepatic steatosis and fibrosis in a mouse model of NASH induced by a choline-deficient, L-amino acid-defined (CDAA) diet. We generated transgenic mice expressing HNP-1 under the control of a β-actin-based promoter. HNP-1 transgenic and wild-type C57BL/6N mice were fed a CDAA diet for 16 weeks to induce hepatic steatosis and fibrosis. Serological and histological features were examined, and the effects of HNP-1 on hepatic stellate cell lines were assessed. HNP-1 transgenic and wild-type mice fed the CDAA diet showed no significant differences in serum alanine aminotransferase levels or the degree of hepatic steatosis based on Oil red O staining and hepatic triglyceride content. In contrast, Sirius Red and Azan staining showed significantly more severe hepatic fibrosis in HNP-1 transgenic mice compared with wild-type mice. In addition, significantly more α-smooth muscle actin-positive hepatic stellate cells were observed in the transgenic mice than in the wild-type mice. Finally, the proliferation of the LI90 hepatic stellate cell line increased in response to HNP-1. Our data indicate that HNP-1 enhances hepatic fibrosis in fatty liver by inducing hepatic stellate cell proliferation. Thus, neutrophil-derived HNP-1 may contribute to the progression of NASH.

IFN-γ abrogates profibrogenic TGF-β signaling in liver by targeting expression of inhibitory and receptor Smads

In a randomized open-labeled multicenter trial with patients suffering from chronic HBV infection, we recently identified a benefit of 9-month IFN-gamma treatment resulting in decreased fibrosis scores and a reduced number of alpha-smooth muscle actin-positive hepatic stellate cells (HSCs). Approaches opposing profibrogenic activities of TGF-beta may be amenable in chronic liver disease. According to experimental models, IFN-gamma counteracts several TGF-beta effects. The crosstalk of IFN-gamma and TGF-beta signaling relevant for fibrogenesis was investigated in primary cultured rat HSCs and a cell line representing activated HSCs. In vitro studies with HSCs demonstrate that TGF-beta-dependent activation of (CAGA)9-MLP-Luc, a Smad3/4 responsive reporter construct, was significantly decreased by IFN-gamma, indicating a TGF-beta antagonizing function. IFN-gamma induced the activity of the Smad7 promoter and Smad7 protein expression via STAT-1 signaling. In contrast to TGF-beta, IFN-gamma was able to induce Smad7 expression in activated HSCs providing increased protein levels for at least 12h. In addition, expression of Smad2/3 was reduced by IFN-gamma and activation of Smads2/3 was abrogated. IFN-gamma displays antifibrotic effects in liver cells via STAT-1 phosphorylation, upregulation of Smad7 expression and impaired TGF-beta signaling.

Alpha-SMA expression in hepatic stellate cells and quantitative analysis of hepatic fibrosis in cirrhosis and in recurrent chronic hepatitis after liver transplantation

Background. The alpha isotype of actin expressed by hepatic stellate cells reflects their activation to myofibroblast-like cell and has been directly related to experimental liver fibrogenesis, and indirectly to human fibrosis in chronic liver disease. Aims. To evaluate the changes in distribution and percentage of alpha-smooth muscle actin-positive hepatic stellate cells and the correlation with the degree of the fibrosis in cirrhotic livers, as well as in patients with recurrent HCV chronic hepatitis after liver transplantation. Methods. Human liver biopsies were divided in four groups: (1) normal livers obtained from cadaveric liver donors ( n = 35), (2) cirrhosis post-HBV hepatitis ( n = 11), (3) cirrhosis post-HCV hepatitis ( n = 10), and (4) post-transplant recurrent HCV chronic hepatitis ( n = 13). Samples were stained with anti-alpha-smooth muscle actin antibody by immunoperoxidase method and semi-quantitatively evaluated. Liver fibrosis was assessed from specimens stained with Masson's trichrome and quantified by computer image analysis. Results. The percentage of alpha-smooth muscle actin-positive hepatic stellate cells was significantly higher in the HBV cirrhosis, HCV cirrhosis and post-transplant HCV recurrent hepatitis groups (36.1 ± 15.2, 23.8 ± 19.7 and 27.8 ± 16.4%, respectively) compared to the liver donor group (2.9 ± 4.0%). The alpha-smooth muscle actin-positive hepatic stellate cells to fibrous tissue ratio were significantly higher in the post-transplant recurrent HCV hepatitis group (2.36 ± 1.12) compared to both the donor livers and the HCV cirrhosis groups (0.74 ± 1.09 and 1.03 ± 0.91, respectively). The alpha-smooth muscle actin-positive hepatic stellate cell percentage and fibrosis correlated positively in the post-transplant recurrent HCV hepatitis group and negatively in the HCV cirrhosis group. No difference in the immunohistochemical and morphometrical variables was found between the HCV cirrhosis and HBV cirrhosis groups. Conclusions. These results indirectly confirm that, in vivo, alpha-smooth muscle actin expression is a reliable marker of hepatic stellate cells activation which precedes fibrous tissue deposition even in the setting of recurrent HCV chronic hepatitis after liver transplantation, and it could be useful to identify the earliest stages of hepatic fibrosis and monitoring the efficacy of the therapy. In the presence of advanced cirrhosis other factors, rather than alpha-smooth muscle actin-positive hepatic stellate cells, may sustain fibrosis deposition.

Hepatic stellate cell immunodetection and cirrhotic evolution of viral hepatitis in liver allografts.

Patients with chronic viral hepatitis are at high risk of developing cirrhosis, but the outcome of the disease in a given patient is unpredictable. Hepatic stellate cells have been demonstrated to be the most important cell type involved in hepatic fibrogenesis, regardless of the cause of the liver injury. The alpha isotype of actin (a phenotypic marker of smooth muscle cells) may be expressed by hepatic stellate cells, reflecting their "activation" to myofibroblast-like cells. The present study aimed to analyze the expression of alpha-smooth muscle actin-positive hepatic stellate cells in liver allografts with recurrent viral hepatitis, and to evaluate whether and how such expression may be related to the outcome of the disease. Using immunohistochemistry and a semi-quantitative scoring system, the expression of a-smooth muscle actin in hepatic stellate cells was analyzed in liver allografts of 17 patients with recurrent viral hepatitis. They included nine patients who developed cirrhosis at the end of follow-up (mean time 23.6 months), and eight patients with no cirrhosis at the end of a comparable follow-up time (mean 30.1 months). In all patients, liver biopsy specimens were obtained between 3 and 6 months (t1) and between 10 and 15 months (t2) after transplantation. Preperfusion biopsy specimens of donor livers served as a baseline (t0). By comparison with the baseline biopsy, an increased number of alpha-smooth muscle actin-expressing hepatic stellate cells was observed in all cases in t1 biopsies. An increase in the amount of alpha-smooth muscle actin-positive hepatic stellate cells in zone 1 at t1 was significantly (P < .006) related to subsequent cirrhotic evolution. In conclusion, in liver allografts with recurrent viral hepatitis, the activation of hepatic stellate cells is an early event. An increased number of alpha-smooth muscle actin-positive hepatic stellate cells in zone 1 may represent an unfavorable event related to cirrhotic evolution.