Interleukin-1 and tumor necrosis factor-α trigger restriction of hepatitis B virus infection via a cytidine deaminase activation-induced cytidine deaminase (AID).

金沢大学医薬保健研究域医学系Virus infection is restricted by intracellular immune responses in host cells, and this is typically modulated by stimulation of cytokines. The cytokines and host factors that determine the host cell restriction against hepatitis B virus (HBV) infection are not well understood. We screened 36 cytokines and chemokines to determine which were able to reduce the susceptibility of HepaRG cells to HBV infection. Here, we found that pretreatment with IL-1β and TNFα remarkably reduced the host cell susceptibility to HBV infection. This effect was mediated by activation of the NF-κB signaling pathway. A cytidine deaminase, activation-induced cytidine deaminase (AID), was up-regulated by both IL-1β and TNFα in a variety of hepatocyte cell lines and primary human hepatocytes. Another deaminase APOBEC3G was not induced by these proinflammatory cytokines. Knockdown of AID expression impaired the anti-HBV effect of IL-1β, and overexpression of AID antagonized HBV infection, suggesting that AID was one of the responsible factors for the anti-HBV activity of IL-1/TNFα. Although AID induced hypermutation of HBV DNA, this activity was dispensable for the anti-HBV activity. The antiviral effect of IL-1/TNFα was also observed on different HBV genotypes but not on hepatitis C virus. These results demonstrate that proinflammatory cytokines IL-1/TNFα trigger a novel antiviral mechanism involving AID to regulate host cell permissiveness to HBV infection

Phenotype-dependent production of des-gamma-carboxy prothrombin in hepatocellular carcinoma

Background Des-gamma-carboxy prothrombin (DCP) is an established tumor marker for hepatocellular carcinoma (HCC), but the precise mechanism of its production remains unknown. We have recently demonstrated that cytoskeletal rearrangement during the phenotypic changes involved in epithelial mesenchymal transition (EMT) plays a crucial role in DCP production through the impairment of vitamin K uptake. However, DCP production in long-lasting severe hypoxic conditions with nutrient deprivation, such as transarterial embolization, remains unknown.Methods We examined the effects of long-lasting hypoxia with nutrient deprivation, as well as the constitutive expression of hypoxia-inducible factor (HIF)-1-alpha, on EMT status, DCP production, and protein synthesis in human hepatoma cell lines by enzyme-linked immunosorbent assay, immunofluorescent studies, and western blotting. Immunohistochemistry findings for DCP, anti-hepatocyte paraffin 1 (Hep Par 1), and vimentin were examined using human resected HCC samples.Results Both severe hypoxia with nutrient deprivation and HIF-1-alpha transfection led to the cessation of DCP production, by attenuating protein synthesis through the hypophosphorylation of mammalian target of rapamycin and its effector proteins, indicative of a further phenotypic shift involving impaired liver-specific protein synthesis. In immunohistochemistry, the distribution of DCP- and Hep Par 1-positive HCC cells was mostly similar and vimentin-positive HCC cells were frequently observed in the areas that were negative for Hep Par 1 and/or DCP.Conclusions HCC cells produce DCP when they undergo mild phenotypic changes. However, when HCC cells adopt mesenchymal properties they lose their capacity for protein synthesis, and the production of DCP is attenuated. Building upon our previous works, it appears that DCP could be a unique tumor marker that reflects the stepwise phenotypic changes of HCC

Ritonavir Blocks Hepatitis E Virus Internalization and Clears Hepatitis E Virus In Vitro with Ribavirin

Hepatitis E virus (HEV) is increasingly recognized as the leading cause of acute hepatitis. Although HEV infections are mostly self-limiting, a chronic course can develop especially in those with immunocompromised state. Ribavirin is currently used to treat such patients. According to various reports on chronic HEV infections, a sustained virological response (SVR) was achieved in approximately 80% of patients receiving ribavirin monotherapy. To increase the SVR rate, drug combination might be a viable strategy, which we attempted in the current study. Ritonavir was identified in our previous drug screening while searching for candidate novel anti-HEV drugs. It demonstrated potent inhibition of HEV growth in cultured cells. In the present study, ritonavir blocked HEV internalization as shown through time-of-addition and immunofluorescence assays. Its combination with ribavirin significantly increased the efficiency of inhibiting HEV growth compared to that shown by ribavirin monotherapy, even in PLC/PRF/5 cells with robust HEV production, and resulted in viral clearance. Similar efficiency was seen for HEV genotypes 3 and 4, the main causes of chronic infection. The present findings provide insight concerning the advantage of combination therapy using drugs blocking different steps in the HEV life cycle (internalization and RNA replication) as a potential novel treatment strategy for chronic hepatitis E

Enterococcus casseliflavus KB1733 Isolated from a Traditional Japanese Pickle Induces Interferon-Lambda Production in Human Intestinal Epithelial Cells

The association between lactic acid bacteria (LAB) and their immunostimulatory effects has attracted considerable attention; however, it remains unclear whether LAB can induce interferon-lambdas (IFN-λs) in human epithelial cells under conditions that do not mimic infection. In this study, we first employed a reporter assay to screen for a potential strain capable of inducing IFN-λ3 among 135 LAB strains derived from traditional Japanese pickles. Next, we assessed the strain’s ability to induce the expression of IFN-λ genes and interferon-stimulated genes (ISGs), and to produce IFN-λs. As a result, we screened and isolated Enterococcus casseliflavus KB1733 (KB1733) as a potential strain capable of inducing IFN-λ3 expression. Furthermore, we clarified that KB1733 induced the expression of IFN-λ genes and ISGs related to antiviral functions, and that KB1733 induced IFN-λ1 and -λ3 expression in a dose-dependent manner up to 10 μg/mL. In addition, KB1733 significantly increased IFN-λ1 production compared to Enterococcus casseliflavus JCM8723T, which belongs to the same genera and species as KB1733. In conclusion, we isolated a unique LAB strain from traditional Japanese pickles that is capable of stimulating IFN-λ production, although further study is needed to investigate how KB1733 protects against viruses in mice and humans