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Transforming growth factor b 1( TGFb1) plays a crucial role in the induction of the epithelial-to-mesenchymal transition (EMT) in hepatocytes, which contributes to the pathogenesis of liver fibrosis. The inhibition of the TGFb1 cascade suppresses EMT and the resultant fibrosis. In this study, we focus on EMT-induced fibrosis in hepatocytes and the epigenetic regulation of the type I collagen gene. Histone acetylation is an important, major epigenetic mechanism that modulates gene transcription. We evaluated the epigenetic regulation of type I collagen in alpha mouse liver 12 hepatocytes (an untransformed mouse cell line) that had undergone EMT after treatment with TGFb1. The histone deacetylase inhibitor trichostatin A (TSA) inhibited EMT; this was reflected by the preservation of epithelial markers and function (E-cadherin and albumin). Fibrosis, the ultimate outcome of EMT, was abolished by TSA; this was indicated by the inhibition of type I collagen deposition. TSA exerted its anti-EMT effects by deactivating the mothers against decapentaplegic homolog 3 (Smad3)/Smad4 transcription complex and by interfering with p300, a coactivator of the type I collagen promoter, and preventing its binding to Smad3. TSA also restored Friend leukemia virus integration 1, an inhibitor of the type I collagen gene. TGFb1-induced EMT and its inhibition by TSA were replicated in human primary hepatocytes. Conclusion: Histone deacetylase inhibition abrogates TGFb1induced EMT in hepatocytes and reverses EMT-induced fibrosis by epigenetic modulation of type I collagen. (HEPATOLOGY 2010;52:1033-1045)

In interferon-alpha (IFN-alpha)/ribavirin combination therapy for chronic hepatitis C (CHC), an enhanced T helper 1 (Th1) response is essential for the eradication of hepatitis C virus (HCV). We aimed to elucidate the role of IFN-alpha or IFN-alpha/ribavirin in dendritic cell (DC) ability to induce Th1 response in HCV infection. We generated monocyte-derived DC from 20 CHC patients and 15 normal subjects driven by granulocyte-macrophage colony-stimulating factor and interleukin 4 (IL-4) without IFN-alpha (GM/4-DC), with IFN-alpha (IFN-DC), with ribavirin (R-DC) or with IFN-alpha/ribavirin (IFN/R-DC) and compared their phenotypes and functions between the groups. We also compared them in 14 CHC patients between who subsequently attained sustained virological response (SVR) and who did not (non-SVR) by 24 weeks of IFN-alpha/ribavirin therapy. Compared with GM/4-DC, IFN-DC displayed higher CD86 expression, but lesser ability to secrete IL-10 and were more potent to prime CD4(+) T cells to secrete IFN-gamma and IL-2. Such differences were more significant in healthy subjects than in CHC patients. No additive effect of ribavirin was observed in DC phenotypes and functions in vitro either which was used alone or in combined with IFN-alpha. However, in the SVR patients, an ability of IFN/R-DC to prime T cells to secrete IFN-gamma and IL-2 was higher than those of IFN-DC and those of IFN/R-DC in the non-SVR group, respectively. In conclusion, DC from CHC patients are impaired in the ability to drive Th1 in response to IFN-alpha. Such DC impairment is restored in vitro by the addition of ribavirin in not all but some patients who cleared HCV by the combination therapy.

Dendritic cells (DCs) are one of the promising tools for enhancing antigen-specific immune responses in clinical settings. Many studies have been performed thus far to verify the efficacy of the DC vaccine in cancer patients; however, the responses have not always been satisfactory, partly because of DC incompetence. To obtain DCs potentially applicable for vaccination of cancer patients, our group sought to establish the strategy of DC generation mainly by modulating culture periods and maturation stimuli. Novel mature DCs that can be generated from monocytes within 3 days by using a combination of OK432 (Streptococcus pyogenes preparation), low-dose prostaglandin E 2 (PGE 2 ), and interferon-α (OPA-DCs) were developed. They strongly express CD83, CD86, and CCR7 and have potent ability to migrate to CCL21. In addition, they were able to activate natural killer and T helper 1 (T H 1) cells and to induce peptide-antigen-specific cytotoxic T lymphocytes more significantly than monocyte-derived DCs stimulated with a conventional cytokine cocktail of tumor necrosis factor-a, interleukin (IL)-1β, IL-6, and PGE 2 (monocyte-conditioned medium [MCM]-mimic DCs). The profound ability of OPA-DCs to stimulate these effectors is attributable to their higher expression of IL-12p70, IL-23, and IL-27 than MCM-mimic DCs, which was supported by the findings that the neutralization of IL-12p70 and IL-23 reduced the T H I priming ability of OPA-DCs. Even when from advanced gastric or colonic cancer patients, OPA-DCs displayed abilities of migration and T H 1 induction comparable to those from healthy subjects. Therefore, OPA-DCs may serve as a feasible vaccine with the potential to enhance T H 1-dominant and cytolytic immune responses against cancers.

Liver fibrosis is a progressive pathologic process that involves deposition of excess extracellular matrix leading to distorted architecture and culminating in cirrhosis. The role of transforming growth factor-beta (TGF-beta) as a key molecule in the development and progression of hepatic fibrosis via the activation of hepatic stellate cells, among other fibroblast populations, is without controversy. We hereby show that TGF-beta1 induces an epithelial-to-mesenchymal transition (EMT) state in mature hepatocytes in vitro. EMT state was marked by significant upregulation of alpha(1)(I) collagen mRNA expression and type I collagen deposition. Similar changes were found in a "normal" mouse hepatocyte cell line (AML12), thus confirming that hepatocytes are capable of EMT changes and type I collagen synthesis. We also show that in hepatocytes in the EMT state, TGF-beta1 induces the snail-1 transcription factor and activates the Smad2/3 pathway. Evidence for a central role of the TGF-beta1/Smad pathway is further supported by the inhibition of EMT by Smad4 silencing using small interference RNA technology. In conclusion, TGF-beta1, a known pro-apoptotic cytokine in mature hepatocytes, is capable of mediating phenotypic changes and plasticity in the form of EMT, resulting in collagen deposition. Our findings support a potentially crucial role for EMT in the development and progression of hepatic fibrogenesis.

Hepatitis C virus (HCV) induces chronic liver disease in hosts which can eventually progresses to liver cirrhosis and hepatocellular carcinoma. However, progression of liver disease is slower in patients with persistently normal levels of alanine aminotransferase (ALT) than in those with active hepatitis. Although distinct immune responses against HCV have been proposed in asymptomatic infection, the role of circulating dendritic cells (DC) in the pathogenesis of these patients remains obscure. To address this issue, we compared the number and function of myeloid DC (MDC) and plasmacytoid DC (PDC) between uninfected individuals and HCV-infected patients with or without elevated ALT levels. Numbers of DC and DC progenitors were significantly lower in patients with chronic active hepatitis than in control subjects. However, no differences were found in the number of DC between normal controls and HCV-infected patients with persistently normal ALT levels. MDC from patients with active hepatitis were less able to polarize naive CD4 T cells into the Th1 phenotype, while their MDC and PDC primed more CD4 T cells producing IL-10 than those from normal controls. Such dysfunction of DC was also observed in patients with persistently normal ALT levels. In conclusion, circulating DC decrease in number predominantly in HCV-infected patients with active hepatitis, and the function of DC is impaired even in those with normal ALT levels.

Dendritic cells (DC) are the most potent antigen-presenting cells that regulate immune responses. One of the mechanisms for hepatitis C virus (HCV) persistence is the ability of HCV to suppress DC function. Direct HCV infection to blood DC has been implicated for DC dysfunction. To clarify the susceptibility of each DC subset to HCV, we used pseudotype vesicular stomatitis virus (VSV) coated with chimeric HCV envelope glycoproteins (E1 and E2). We demonstrate that pseudotype VSV enters myeloid DC (MDC) but not plasmacytoid DC (PDC). The highest efficiency of pseudotype VSV entry to MDC was observed when MDC were cultured with GM-CSF. Such efficiency decreased when MDC are matured with the treatment of IL-4, CpG oligodeoxynucleotide, or CD40 ligand. Mannan inhibited pseudotype VSV entry to MDC, but Ca2+ chelators failed to do so. These results show that pseudotype VSV possessing HCV-E1 and E2 enters immature MDC through the interaction with lectins in a Ca2+-independent manner.