Natural killer (NK) and hepatitis B virus (HBV)‐specific T cells are functionally impaired in chronic hepatitis B (CHB). Understanding to what extent nucleos(t)ide analogue (NUC) therapy can improve T‐ and NK‐cell responses is important in the perspective of immunomonitoring strategies for a safe and earlier NUC withdrawal and of novel combination therapies based on modulation of antiviral immunity. To gain further insights into T/NK‐cell interplay, we studied NK‐cell phenotype and function in hepatitis B e antigen–negative chronic HBV patients either untreated (25) or NUC treated (36 hepatitis B surface antigen [HBsAg]⁺ and 10 HBsAg^–/hepatitis B surface antibody [anti‐HBs]⁺). Interferon‐gamma, interleukin‐2, and tumor necrosis factor alpha (TNF‐α) production by HBV‐specific T cells was also analyzed in NUC‐treated patients. NK cells from chronic naïve patients showed an “inflammatory” phenotype defined by increased expression of TNF‐related apoptosis‐inducing ligand (TRAIL), CD38, and Ki67 that significantly declined upon viremia suppression and alanine aminotransferase normalization induced by NUC therapy. Reversion to a quiescent NK‐cell phenotype was associated with restoration of the HBV‐specific T‐cell function. T‐ and NK‐cell responses showed an inverse correlation, with an opposite behavior in individual NUC‐treated patients. NK‐cell depletion as well as TRAIL and NKG2D pathway blockade induced a significant improvement of the HBV‐specific T‐cell function. Conclusions: NK cells can express regulatory activity on T cells in NUC‐treated patients with prevalent inhibition of CD4 T cells, likely needed to limit persistent T‐cell activation. NK‐cell phenotype is modulated by NUC therapy and its reversion to quiescence mirrors efficient HBV‐specific T‐cell responses. Thus, changes of NK‐cell phenotype may predict acquisition of antiviral control before anti‐HBs seroconversion and represent the groundwork for future studies aimed at assessing whether NK phenotyping can be translated into the clinical practice to guide NUC suspension.(Hepatology 2015;62:1697–1709)

Hepatitis C virus infection (HCV) represents a unique model to characterize, from early to late stages of infection, the T cell differentiation process leading to exhaustion of human CD8+ T cells. Here we show that in early HCV infection, exhaustion-committed virus-specific CD8+ T cells display a marked upregulation of transcription associated with impaired glycolytic and mitochondrial functions, that are linked to enhanced ataxia-telangiectasia mutated (ATM) and p53 signaling. After evolution to chronic infection, exhaustion of HCV-specific T cell responses is instead characterized by a broad gene downregulation associated with a wide metabolic and anti-viral function impairment, which can be rescued by histone methyltransferase inhibitors. These results have implications not only for treatment of HCV-positive patients not responding to last-generation antivirals, but also for other chronic pathologies associated with T cell dysfunction, including cancer.

RNA interference molecules have some advantages as cancer therapeutics, including a proved efficacy on both wild-type (WT) and mutated transcripts and an extremely high sequence-specificity. The most significant hurdle to be overcome if exogenous small interfering RNAs (siRNA) is to be used therapeutically is the specific, effective, nontoxic delivery of siRNA to its intracellular site of action. At present, human applications are confined almost exclusively to targets within the liver, where the delivery systems naturally accumulate, and extra-hepatic targets remain a challenge. Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that has recently been shown to contribute to the cell growth and progression of human neuroblastoma (NB). We investigated its potential as a therapeutic target in NB by generating anti-GD₂-targeted nanoparticles that carry ALK-directed siRNA, which are specifically and efficiently delivered to GD₂-expressing NB cells. Relative to free ALK-siRNA, anti-GD₂-targeted liposomal formulations of ALK-siRNA had low plasma clearance, increased siRNA stability, and improved binding, uptake, silencing and induction of cell death, and specificity for NB cells. In NB xenografts, intravenous (i.v.) injection of the targeted ALK-siRNA liposomes showed gene-specific antitumor activity with no side effects. ALK-selective siRNA entrapped in anti-GD₂-targeted nanoparticles is a promising new modality for NB treatment.

Chronic hepatitis B virus (HBV) infection represents a worldwide public health concern with approximately 250 million people chronically infected and at risk of developing liver cirrhosis and hepatocellular carcinoma. Nucleos(t)ide analogues (NUC) are the most widely used therapies for HBV infection, but they often require long-lasting administration to avoid the risk of HBV reactivation at withdrawal. Therefore, there is an urgent need to develop novel treatments to shorten the duration of NUC therapy by accelerating virus control, and to complement the effect of available anti-viral therapies. In chronic HBV infection, virus-specific T cells are functionally defective, and this exhaustion state is a key determinant of virus persistence. Reconstitution of an efficient anti-viral T cell response may thus represent a rational strategy to treat chronic HBV patients. In this perspective, the enhancement of adaptive immune responses by a checkpoint inhibitor blockade, specific T cell vaccines, lymphocyte metabolism targeting, and autologous T cell engineering, including chimeric antigen receptor (CAR) and TCR-redirected T cells, constitutes a promising immune modulatory approach for a therapeutic restoration of protective immunity. The advances of the emerging immune-based therapies in the setting of the HBV research field will be outlined.