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 |

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), a monogenic disorder caused by AIRE mutations, presents with several autoimmune diseases. Among these, endocrine organ failure is widely recognized, but the prevalence, immunopathogenesis, and treatment of non-endocrine manifestations such as pneumonitis remain poorly characterized. We enrolled 50 patients with APECED in a prospective observational study and comprehensively examined their clinical and radiographic findings, performed pulmonary function tests, and analyzed immunological characteristics in blood, bronchoalveolar lavage fluid, and endobronchial and lung biopsies. Pneumonitis was found in >40% of our patients, presented early in life, was misdiagnosed despite chronic respiratory symptoms and accompanying radiographic and pulmonary function abnormalities, and caused hypoxemic respiratory failure and death. Autoantibodies against BPIFB1 and KCNRG and the homozygous c.967_979del13 AIRE mutation are associated with pneumonitis development. APECED pneumonitis features compartmentalized immunopathology, with accumulation of activated neutrophils in the airways and lymphocytic infiltration in intraepithelial, submucosal, peribronchiolar, and interstitial areas. Beyond APECED, we extend these observations to lung disease seen in other conditions with secondary AIRE deficiency (thymoma and RAG deficiency). Aire-deficient mice had similar compartmentalized cellular immune responses in the airways and lung tissue, which was ameliorated by deficiency of T and B lymphocytes. Accordingly, T and B lymphocyte–directed immunomodulation controlled symptoms and radiographic abnormalities and improved pulmonary function in patients with APECED pneumonitis. Collectively, our findings unveil lung autoimmunity as a common, early, and unrecognized manifestation of APECED and provide insights into the immunopathogenesis and treatment of pulmonary autoimmunity associated with impaired central immune tolerance.

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...