We have shown that cellular inhibitor of apoptosis proteins (cIAPs) impair clearance of hepatitis B virus (HBV) infection by preventing TNF-mediated killing/death of infected cells. A key question, with profound therapeutic implications, is whether this finding can be translated to the development of drugs that promote elimination of infected cells. Drug inhibitors of cIAPs were developed as cancer therapeutics to promote TNF-mediated tumor killing. These drugs are also known as Smac mimetics, because they mimic the action of the endogenous protein Smac/Diablo that antagonizes cIAP function. Here, we show using an immunocompetent mouse model of chronic HBV infection that birinapant and other Smac mimetics are able to rapidly reduce serum HBV DNA and serum HBV surface antigen, and they promote the elimination of hepatocytes containing HBV core antigen. The efficacy of Smac mimetics in treating HBV infection is dependent on their chemistry, host CD4 + T cells, and TNF. Birinapant enhances the ability of entecavir, an antiviral nucleoside analog, to reduce viral DNA production in HBV-infected animals. These results indicate that birinapant and other Smac mimetics may have efficacy in treating HBV infection and perhaps, other intracellular infections.hepatitis B virus | cellular inhibitor of apoptosis proteins | TNF |

The concept that extracellular vesicles (EVs) from the diet can be absorbed by the intestinal tract of the consuming organism, be bioavailable in various organs, and in-turn exert phenotypic changes is highly debatable. Here, we isolate EVs from both raw and commercial bovine milk and characterize them by electron microscopy, nanoparticle tracking analysis, western blotting, quantitative proteomics and small RNA sequencing analysis. Orally administered bovine milk-derived EVs survive the harsh degrading conditions of the gut, in mice, and is subsequently detected in multiple organs. Milk-derived EVs orally administered to mice implanted with colorectal and breast cancer cells reduce the primary tumor burden. Intriguingly, despite the reduction in primary tumor growth, milk-derived EVs accelerate metastasis in breast and pancreatic cancer mouse models. Proteomic and biochemical analysis reveal the induction of senescence and epithelial-to-mesenchymal transition in cancer cells upon treatment with milk-derived EVs. Timing of EV administration is critical as oral administration after resection of the primary tumor reverses the pro-metastatic effects of milk-derived EVs in breast cancer models. Taken together, our study provides context-based and opposing roles of milk-derived EVs as metastasis inducers and suppressors.

The immune response to embryonic stem (ES) cells is still poorly understood. In this study, we addressed the adaptive cellular immune response to undifferentiated and differentiated ES cells infected with lymphocytic choriomeningitis virus (LCMV), a vertically transmitted pathogen in mice and humans. In contrast to the prevailing view, we found that undifferentiated and differentiated murine ES cells express MHC class I molecules, although at low levels. When cocultured with LCMV-infected ES cells, syngeneic but not allogeneic LCMV-specific CTL secrete IFN-γ. Strikingly, LCMV-specific CTL do not efficiently kill LCMV-infected ES cells. ES cells showed high-level expression of the serine protease inhibitor 6, an endogenous inhibitor of the CTL-derived cytotoxic effector molecule granzyme B. Down-regulation of serpin-6 by RNA interference sensitized ES cells for CTL-induced cell death. The results of this study suggest that LCMV-infected murine ES cells present viral Ags and are recognized by LCMV-specific CTL in a MHC class I-restricted manner, yet resist CTL-mediated lysis through high-level expression of serine protease inhibitor 6.

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Hepatitis B virus (HBV) infection can result in a spectrum of outcomes from immune-mediated control to disease progression, cirrhosis, and liver cancer. The host molecular pathways that influence and contribute to these outcomes need to be defined. Using an immunocompetent mouse model of chronic HBV infection, we identified some of the host cellular and molecular factors that impact on infection outcomes. Here, we show that cellular inhibitor of apoptosis proteins (cIAPs) attenuate TNF signaling during hepatitis B infection, and they restrict the death of infected hepatocytes, thus allowing viral persistence. Animals with a liver-specific cIAP1 and total cIAP2 deficiency efficiently control HBV infection compared with WT mice. This phenotype was partly recapitulated in mice that were deficient in cIAP2 alone. These results indicate that antagonizing the function of cIAPs may promote the clearance of HBV infection.hepatitis B virus | cellular inhibitor of apoptosis proteins | cIAP1 | cIAP2 | TNF I t is estimated that 2 billion people currently living in the world have been infected with hepatitis B virus (HBV), and among these, 360 million people are chronic carriers (1). HBV causes 780,000 deaths each year and is responsible for 50% and 33% of deaths attributable to liver cancer and cirrhosis, respectively (2). The host factors and molecular pathways that impact on HBV disease and clinical outcomes are not well-understood (3). What is becoming clear is that immunosuppressive agents and particularly, biological agents, including anti-TNF therapy, can cause major flares in HBV-related disease, leading to morbidity and mortality (4, 5). Animal models and particularly, immunocompetent mouse models of persistent HBV infection have been used to dissect host-pathogen interactions that influence infection outcomes (6-8). These animal models can be used to define host cell signaling and cell death pathways that contribute to the persistence or control of HBV infection.We induced HBV infection in two mouse models to examine the relevance of host factors in controlling infection. In a model that mimics partial control of infection, we were able to determine the importance of host cell signaling pathways through the use of gene-targeted mice. By identifying the relevant host cell signaling molecules that impact on HBV clinical outcomes, it may be possible to develop therapeutics that target host cell pathways and alter the course of HBV-related disease. ResultsChronic HBV Infection Can Be Mimicked in a Mouse Model. We used a previously described method to induce HBV persistence in immunocompetent mice (6). A plasmid containing a 1.2 over length sequence of HBV genotype A was hydrodynamically injected into mice, but in contrast to the previously published protocol, we did not anesthetize animals. Using this modified technique, we did not observe any injection-associated mortality, and C57BL/6 mice showed persistently high serum HBV DNA levels over 8-12 wk (Fig. 1A). Eventually, HBV DNA levels fell in all animals along with t...