Upregulation of class I major histocompatibility complex antigens by interferon gamma is necessary for T-cell-mediated elimination of recombinant adenovirus-infected hepatocytes in vivo

Polymeric nanoparticle gel for intracellular mRNA delivery and immunological reprogramming of tumors

Immuno-oncology therapies have been of great interest with the goal of inducing sustained tumor regression, but clinical results have demonstrated the need for improved and widely applicable methods. An antigen-free method of cancer immunotherapy can stimulate the immune system to recruit lymphocytes and produce immunostimulatory factors without prior knowledge of neoantigens, while local delivery reduces the risk of systemic toxicity. To improve the interactions between tumor cells and cytotoxic lymphocytes, a gene delivery nanoparticle platform was engineered to reprogram the tumor microenvironment (TME) in situ to be more immunostimulatory by inducing tumor-associated antigen-presenting cells (tAPCs) to activate cytotoxic lymphocytes against the tumor. Biodegradable, lipophilic poly (beta-amino ester) (PBAE) nanoparticles were synthesized and used to co-deliver mRNA constructs encoding a signal 2 co-stimulatory molecule (4-1BBL) and a signal 3 immuno-stimulatory cytokine (IL-12), along with a nucleic acid-based immunomodulatory adjuvant. Nanoparticles are combined with a thermoresponsive block copolymer for gelation at the injection site for local NP retention at the tumor. The reprogramming nanoparticle gel synergizes with immune checkpoint blockade (ICB) to induce tumor regression and clearance in addition to resistance to tumor rechallenge at a distant site. In vitro and in vivo studies reveal increases in immunostimulatory cytokine production and recruitment of immune cells as a result of the nanoparticles. Intratumoral injection of nanoparticles encapsulating mRNA encoding immunostimulatory agents and adjuvants via an injectable thermoresponsive gel has great translational potential as an immuno-oncology therapy that can be accessible to a wide range of patients.

JAK-STAT activation contributes to cytotoxic T cell-mediated basal cell death in human chronic lung allograft dysfunction

Chronic lung allograft dysfunction (CLAD) is the leading cause of death in lung transplant recipients. CLAD is characterized clinically by a persistent decline in pulmonary function and histologically by the development of airway-centered fibrosis known as bronchiolitis obliterans. There are no approved therapies to treat CLAD, and the mechanisms underlying its development remain poorly understood. We performed single-cell RNA-Seq and spatial transcriptomic analysis of explanted tissues from human lung recipients with CLAD, and we performed independent validation studies to identify an important role of Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling in airway epithelial cells that contributes to airway-specific alloimmune injury. Specifically, we established that activation of JAK-STAT signaling leads to upregulation of major histocompatibility complex 1 (MHC-I) in airway basal cells, an important airway epithelial progenitor population, which leads to cytotoxic T cell-mediated basal cell death. This study provides mechanistic insight into the cell-to-cell interactions driving airway-centric alloimmune injury in CLAD, suggesting a potentially novel therapeutic strategy for CLAD prevention or treatment.

Tbc1d10c is a selective, constitutive suppressor of the CD8 T-cell anti-tumor response

Cancer immunotherapy approaches target signaling pathways that are highly synonymous between CD4 and CD8 T-cell subsets and, therefore, often stimulate nonspecific lymphocyte activation, resulting in cytotoxicity to otherwise healthy tissue. The goal of our study was to identify intrinsic modulators of basic T lymphocyte activation pathways that could discriminately bolster CD8 anti-tumor effector responses. Using a Tbc1d10c null mouse, we observed marked resistance to a range of tumor types conferred by Tbc1d10c deficiency. Moreover, tumor-bearing Tbc1d10c null mice receiving PD-1 or CTLA-4 monotherapy exhibited a 33% or 90% cure rate, respectively. While Tbc1d10c was not expressed in solid tumor cells, Tbc1d10c disruption selectively augmented CD8 T-cell activation and cytotoxic effector responses and adoptive transfer of CD8 T cells alone was sufficient to recapitulate Tbc1d10c null tumor resistance. Mechanistically, Tbc1d10c suppressed CD8 T-cell activation and anti-tumor function by intersecting canonical NF-κB pathway activation via regulation of Map3k3-mediated IKKβ phosphorylation. Strikingly, none of these cellular or molecular perturbations in the NF-κB pathway were featured in Tbc1d10c null CD4 T cells. Our findings identify a Tbc1d10c-Map3k3-NF-κB signaling axis as a viable therapeutic target to promote CD8 T-cell anti-tumor immunity while circumventing CD4 T cell-associated cytotoxicity and NF-κB activation in tumor cells.

Adenovirus vector and mRNA vaccines: Mechanisms regulating their immunogenicity

Replication-incompetent adenovirus (Ad) vector and mRNA-lipid nanoparticle (LNP) constructs represent two modular vaccine platforms that have attracted substantial interest over the past two decades. Due to the COVID-19 pandemic and the rapid development of multiple successful vaccines based on these technologies, there is now clear real-world evidence of the utility and efficacy of these platforms. Considerable optimization and refinement efforts underpin the successful application of these technologies. Despite this, our understanding of the specific pathways and processes engaged by these vaccines to stimulate the immune response remains incomplete. This review will synthesize our current knowledge of the specific mechanisms by which CD8⁺ T cell and antibody responses are induced by each of these vaccine platforms, and how this can be impacted by specific vaccine construction techniques. Key gaps in our knowledge are also highlighted, which can hopefully focus future studies.

Conductive Gas Plasma Treatment Augments Tumor Toxicity of Ringer's Lactate Solutions in a Model of Peritoneal Carcinomatosis

Reactive species generated by medical gas plasma technology can be enriched in liquids for use in oncology targeting disseminated malignancies, such as metastatic colorectal cancer. Notwithstanding, reactive species quantities depend on the treatment mode, and we recently showed gas plasma exposure in conductive modes to be superior for cancer tissue treatment. However, evidence is lacking that such a conductive mode also equips gas plasma-treated liquids to confer augmented intraperitoneal anticancer activity. To this end, employing atmospheric pressure argon plasma jet kINPen-treated Ringer's lactate (oxRilac) in a CT26-model of colorectal peritoneal carcinomatosis, we tested repeated intraabdominal injection of such remotely or conductively oxidized liquid for antitumor control and immunomodulation. Enhanced reactive species formation in conductive mode correlated with reduced tumor burden in vivo, emphasizing the advantage of conduction over the free mode for plasma-conditioned liquids. Interestingly, the infiltration of lymphocytes into the tumors was equally enhanced by both treatments. However, significantly lower levels of interleukin (IL)4 and IL13 and increased levels of IL2 argue for a shift in intratumoral T-helper cell subpopulations correlating with disease control. In conclusion, our data argue for using conductively over remotely prepared plasma-treated liquids for anticancer treatment.

Parallels Between the Antiviral State and the Irradiated State

Improved understanding of host antiviral defense and antitumor immunity have elucidated molecular pathways important to both processes. During viral infection, RNA or DNA in the host cell serves as a danger signal that initiates the antiviral response. Recent studies have elucidated similarities in the signaling pathways activated by viruses and the signaling pathways induced by tumor DNA that is released into the cytoplasm of irradiated tumor cells. Both the host defense to viral infection and the sterile inflammation provoked by radiotherapy induce a type I interferon response that is necessary for pathogen control and immune-mediated tumor control, respectively. These findings have led to the hypothesis that radiotherapy employs a form of viral mimicry.

Downregulation of Interferon-γ Receptor Expression Endows Resistance to Anti-Programmed Death Protein 1 Therapy in Colorectal Cancer

Immune checkpoint inhibitors have emerged as a frontline treatment of a variety of malignancies. However, only a subset of patients respond to these therapies, and many initial responders eventually develop resistance, leading to tumor relapse. Programmed death protein 1 is one of the checkpoint inhibitors that is expressed on activated T cells and suppresses the antitumor immune response when binding to its ligand, programmed death ligand 1, on tumor cells. Previous studies indicated that loss-of-function mutations in the IFN-γ pathway could result in acquired resistance to immune checkpoint inhibitors in human patients with cancer. Here, we investigated the effects of the IFN-γ receptor downexpression on the response to an anti-PD-1 antibody (αPD1) in a murine colorectal cancer model and the underlying mechanisms of resistance. IFN-γ receptor (IFNGR) 1 was knocked down in MC38 cells, a murine colon adenocarcinoma cell line using IFNGR1 short hairpin RNA (shRNA) lentiviral particles. Then, MC38 IFNGR1 knockdown (KD) cells and negative control (SC) cells were used in this study. In the C57BL/6 xenograft model, the KD tumor demonstrated resistance to αPD1 in comparison with SC cells. The observed treatment resistance might be associated with reduced tumor-infiltrating immune cells (TILs). When mixed, the resistant (KD) and control cells (SC) grew in spatially separated tumor areas, and αPD1 did not impact this pattern of spatial distribution. Our findings have proved that downregulation of the IFNGR1 endowed resistance to αPD1 and provided the potential mechanisms involving the TILs. SIGNIFICANCE STATEMENT: Immunological checkpoint blockades have achieved substantial efficacy in a variety of tumors. However, only a subset of patients respond to these therapies, and innate and acquired resistance is widely present. Our study found that the downregulation of the IFN-γ receptor caused resistance to an anti-PD-1 antibody in a murine colorectal cancer model associated with the reduced tumor-infiltrating lymphocytes. Our findings have substantial implications for improving the efficacy of checkpoint blockades.

Effect of Vitamin D on Experimental Autoimmune Neuroinflammation Is Dependent on Haplotypes Comprising Naturally Occurring Allelic Variants of CIITA (Mhc2ta)

An increasing body of evidence associates low vitamin D levels with increased risk of multiple sclerosis (MS), suggesting the possibility of a gene-environment interaction for this environmental factor in MS pathogenesis. Moreover, it has been shown that vitamin D downregulates major histocompatibility complex (MHC) class II expression in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. We here report about the impact of a dietary vitamin D supplementation on EAE in the rat strains having functionally relevant allelic variations in the CIITA (Mhc2ta) gene, a master regulator of MHC class II expression. Full length myelin oligodendrocyte glycoprotein (MOG)-EAE was induced in DA.PVG^av1-Vra4 congenic rats harboring the Vra4 locus from PVG strain in the EAE- susceptible DA background, and compared to the parental strains. The congenic rats fed with either vitamin D supplemented, deprived or regular diet developed an intermediate clinical EAE phenotype, in contrast to DA and PVG strains. Immunopathological studies revealed vitamin D dose-dependent effect on demyelination and inflammatory infiltration of the central nervous system (CNS), expression of MHC class II and CIITA, as well as downregulation of a range of pro-inflammatory genes. Taken together, our findings demonstrate an impact of vitamin D on the target tissue pathology and peripheral immune response during EAE in DA.PVG^av1-Vra4 congenic strain. Thereby, our data provide evidence of a modulatory effect of vitamin D in context of genetic variances in the Vra4 locus/Mhc2ta gene in MS-like neuroinflammation, with potential relevance for the human demyelinating disease.

Multiplexed relative and absolute quantitative immunopeptidomics reveals MHC I repertoire alterations induced by CDK4/6 inhibition

Peptides bound to class I major histocompatibility complexes (MHC) play a critical role in immune cell recognition and can trigger an antitumor immune response in cancer. Surface MHC levels can be modulated by anticancer agents, altering immunity. However, understanding the peptide repertoire's response to treatment remains challenging and is limited by quantitative mass spectrometry-based strategies lacking normalization controls. We describe an experimental platform that leverages recombinant heavy isotope-coded peptide MHCs (hipMHCs) and multiplex isotope tagging to quantify peptide repertoire alterations using low sample input. HipMHCs improve quantitative accuracy of peptide repertoire changes by normalizing for variation across analyses and enable absolute quantification using internal calibrants to determine copies per cell of MHC antigens, which can inform immunotherapy design. Applying this platform in melanoma cell lines to profile the immunopeptidome response to CDK4/6 inhibition and interferon-γ - known modulators of antigen presentation - uncovers treatment-specific alterations, connecting the intracellular response to extracellular immune presentation.

Allo-priming as a universal anti-viral vaccine: protecting elderly from current COVID-19 and any future unknown viral outbreak

BACKGROUND

We present the rationale for a novel allo-priming approach to serve the elderly as a universal anti-virus vaccine, as well serving to remodel the aging immune system in order to reverse immunosenescence and inflammaging. This approach has the potential to protect the most vulnerable from disease and provide society an incalculable economic benefit. Allo-priming healthy elderly adults is proposed to provide universal protection from progression of any type of viral infection, including protection against progression of the current outbreak of COVID-19 infection, and any future variants of the causative SARS-CoV-2 virus or the next 'Disease X'. Allo-priming is an alternative approach for the COVID-19 pandemic that provides a back-up in case vaccination strategies to elicit neutralizing antibody protection fails or fails to protect the vulnerable elderly population. The allo-priming is performed using activated, intentionally mismatched, ex vivo differentiated and expanded living Th1-like cells (AlloStim^®) derived from healthy donors currently in clinical use as an experimental cancer vaccine. Multiple intradermal injections of AlloStim^® creates a dominate titer of allo-specific Th1/CTL memory cells in circulation, replacing the dominance of exhausted memory cells of the aged immune system. Upon viral encounter, by-stander activation of the allo-specific memory cells causes an immediate release of IFN-ϒ, leading to development of an "anti-viral state", by-stander activation of innate cellular effector cells and activation of cross-reactive allo-specific CTL. In this manner, the non-specific activation of allo-specific Th1/CTL initiates a cascade of spatial and temporal immune events which act to limit the early viral titer. The release of endogenous heat shock proteins (HSP) and DAMP from lysed viral-infected cells, in the context of IFN-ϒ, creates of conditions for in situ vaccination leading to viral-specific Th1/CTL immunity. These viral-specific Th1/CTL provide sterilizing immunity and memory for protection from disease recurrence, while increasing the pool of Th1/CTL in circulation capable of responding to the next viral encounter.

CONCLUSION

Allo-priming has potential to provide universal protection from viral disease and is a strategy to reverse immunosenescence and counter-regulate chronic inflammation (inflammaging). Allo-priming can be used as an adjuvant for anti-viral vaccines and as a counter-measure for unknown biological threats and bio-economic terrorism.

Tumor heterogeneity and clonal cooperation influence the immune selection of IFN-γ-signaling mutant cancer cells

PD-1/PD-L1 blockade can promote robust tumor regression yet secondary resistance often occurs as immune selective pressure drives outgrowth of resistant tumor clones. Here using a genome-wide CRISPR screen in B16.SIY melanoma cells, we confirm Ifngr2 and Jak1 as important genes conferring sensitivity to T cell-mediated killing in vitro. However, when implanted into mice, these Ifngr2- and Jak1-deficient tumors paradoxically are better controlled immunologically. This phenotype maps to defective PD-L1 upregulation on mutant tumor cells, which improves anti-tumor efficacy of CD8+ T cells. To reconcile these observations with clinical reports of anti-PD-1 resistance linked to emergence of IFN-γ signaling mutants, we show that when mixed with wild-type tumor cells, IFN-γ-insensitive tumor cells indeed grow out, which depends upon PD-L1 expression by wild-type cells. Our results illustrate the complexity of functions for IFN-γ in anti-tumor immunity and demonstrate that intratumor heterogeneity and clonal cooperation can contribute to immunotherapy resistance.

Cellular Therapies in Chronic Granulomatous Disease

Allogeneic hematopoietic stem cell transplantation (HSCT) has become the main curative treatment in patients with chronic granulomatous disease (CGD). CGD is caused by inherited defects of the phagolysomal NADPH-oxidase, leading to a lifelong propensity for invasive infections and granulomatous inflammation. After successful allogeneic HSCT, chronic infections and inflammation resolve and quality-of-life improves. Favorable long-term outcome after HSCT is dependent on the prevention of primary and secondary graft failure (GF), including falling myeloid donor chimerism (DC) below 10 %, and chronic graft-vs.-host-disease (cGVHD). The risk of GF and GvHD increases with the use of HLA-incompatible donors and this may outweigh the benefits of HSCT, mainly in patients with severe co-morbidities and in asymptomatic patients with residual NADPH-oxidase function. Seventeen scientific papers have reported on a total of 386 CGD-patients treated by HSCT with HLA-matched family/sibling (MFD/MSD), 9/10-/10/10-matched-unrelated volunteer (MUD) and cord blood donors. The median OS/EFS-rate of these 17 studies was 91 and 82%, respectively. The median rates of GF, cGVHD and de-novo autoimmune diseases were 14, 10, and 12%, respectively. Results after MFD/MSD and 10/10-MUD-transplants were rather similar, but outcome in adults with significant co-morbidities and after transplants with 9/10 HLA-MUD were less successful, mainly due to increased GF and chronic GVHD. Transplantation protocols using T-cell depleted haploidentical donors with post-transplant cyclophosphamide or TCR-alpha/beta depletion have recently reported promising results. Autologous gene-therapy after lentiviral transduction of HSC achieved OS/EFS-rates of 78/67%, respectively. Careful retrospective and prospective studies are mandatory to ascertain the most effective cellular therapies in patients with CGD.

Advances in Molecular biomarker for early diagnosis of Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative joint disease. The pathogenesis is poorly understood. What is known is that OA is characterized by imbalance in anabolic and catabolic gene expression in articular chondrocytes. This results in bone on bone articulations resulting in impaired mobility and joint pain. Although the cause of OA is unknown, comorbidities include: aging, obesity, and mechanical stress. Currently the only diagnostic modalities are radiology and physical examination, and early detection is rare. Biomarkers are quantifiable substances, and their presence can be suggestive of a certain phenomenon or disease. Biomarkers are popular for early diagnosis for pathological conditions in the fields of oncology, cardiology, and endocrinology. This review has systematically reviewed the literature about biomarkers in the field of OA, specifically protein, miRNA, and metabolic biomarkers found in the blood, urine, and synovial fluid.

Cystic Fibrosis Gene Therapy: Looking Back, Looking Forward

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene that encodes a cAMP-regulated anion channel. Although CF is a multi-organ system disease, most people with CF die of progressive lung disease that begins early in childhood and is characterized by chronic bacterial infection and inflammation. Nearly 90% of people with CF have at least one copy of the ΔF508 mutation, but there are hundreds of CFTR mutations that result in a range of disease severities. A CFTR gene replacement approach would be efficacious regardless of the disease-causing mutation. After the discovery of the CFTR gene in 1989, the in vitro proof-of-concept for gene therapy for CF was quickly established in 1990. In 1993, the first of many gene therapy clinical trials attempted to rescue the CF defect in airway epithelia. Despite the initial enthusiasm, there is still no FDA-approved gene therapy for CF. Here we discuss the history of CF gene therapy, from the discovery of the CFTR gene to current state-of-the-art gene delivery vector designs. While implementation of CF gene therapy has proven more challenging than initially envisioned; thanks to continued innovation, it may yet become a reality.

The hemochromatosis protein HFE 20 years later: An emerging role in antigen presentation and in the immune system

Introduction

Since its discovery, the hemochromatosis protein HFE has been primarily defined by its role in iron metabolism and homeostasis, and its involvement in the genetic disease termed hereditary hemochromatosis (HH). While HH patients are typically afflicted by dysregulated iron levels, many are also affected by several immune defects and increased incidence of autoimmune diseases that have thereby implicated HFE in the immune response. Growing evidence has supported an immunological role for HFE with recent studies describing HFE specifically as it relates to MHC I antigen presentation.

Methods/Results

Here, we present a comprehensive overview of the relationship between iron metabolism, HFE, and the immune system to better understand the origin and cause of immune defects in HH patients. We further describe the role of HFE in MHC I antigen presentation and its potential to impair autoimmune responses in homeostatic conditions, a mechanism which may be exploited by tumors to evade immune surveillance.

Conclusion

Overall, this increased understanding of the role of HFE in the immune response sets the stage for better treatment and management of HH and other iron‐related diseases, as well as of the immune defects related to this condition.

Immediate Dysfunction of Vaccine-Elicited CD8+ T Cells Primed in the Absence of CD4+ T Cells

CD4(+) T cell help is critical for optimal CD8(+) T cell memory differentiation and maintenance in many experimental systems. In addition, many reports have identified reduced primary CD8(+) T cell responses in the absence of CD4(+) T cell help, which often coincides with reduced Ag or pathogen clearance. In this study, we demonstrate that absence of CD4(+) T cells at the time of adenovirus vector immunization of mice led to immediate impairments in early CD8(+) T cell functionality and differentiation. Unhelped CD8(+) T cells exhibited a reduced effector phenotype, decreased ex vivo cytotoxicity, and decreased capacity to produce cytokines. This dysfunctional state was imprinted within 3 d of immunization. Unhelped CD8(+) T cells expressed elevated levels of inhibitory receptors and exhibited transcriptomic exhaustion and anergy profiles by gene set enrichment analysis. Dysfunctional, impaired effector differentiation also occurred following immunization of CD4(+) T cell-deficient mice with a poxvirus vector. This study demonstrates that following priming with viral vectors, CD4(+) T cell help is required to promote both the expansion and acquisition of effector functions by CD8(+) T cells, which is accomplished by preventing immediate dysfunction.

Cytotoxic T lymphocyte antigen 4 decreases humoral and cellular immunity by adenovirus to enhance target GFP gene transfer in C57BL/6 mice

Adenoviruses (Ad) are once potential and promising vectors for gene delivery, but the immunogenicity attenuates its transfer efficiency. Cytotoxic T lymphocyte antigen 4 (CTLA-4) can inhibit T cell immunity. Thus, we aimed to study the effect of CTLA-4 in the process of Ad-mediated gene transfer. The C57BL/6 mice were injected by Ad vectors at twice, and CTLA-4 was administrated after the first Ad injection. Then, the CD3(+)CD4(+) T cells and circulating levels of IL-2, IL-4, and anti-Ad IgG were decreased by CTLA-4, while Ad generated immune responses. The green fluorescence protein (GFP) expressions of tissues were enhanced by CTLA-4 till injection of Ad at twice. Our results indicate that CTLA-4 can inhibit humoral and cellular immunity by adenovirus generation to enhance GFP delivery, and provide a potential way to assist in Ad-mediated gene transfer.

TANK-binding kinase 1-dependent or -independent signaling elicits the cell-type-specific innate immune responses induced by the adenovirus vector

Adenovirus vectors (Adv) elicit innate immune responses via several pattern-recognition receptors. Although it has been suggested that various Adv-induced mechanisms play important roles in the induction of innate immunity in vitro, the impacts of these mechanisms in vivo remain unclear. Viral nucleic acids elicit innate immune responses through the recognition of cytosolic nucleic acid sensors and transduce intracellular signals to TANK-binding kinase (TBK) 1. In this study, to determine the impacts of viral nucleic acids on innate immune responses in vivo, we administered transgene-expressing Adv to Tbk1-deficient mice. The systemic Adv administration failed to induce type I interferons (type I IFNs) in the spleen, but not the liver, of Tbk1-deficient mice, resulting in the increase of transgene-expressing cells in the spleen, but not the liver. Moreover, Adv failed to induce type I IFNs in the bone-marrow-derived dendritic cells, but not the mouse embryonic fibroblasts, from Tbk1-deficient mice in vitro. These results support the idea that Adv elicit innate immunity in immune cells and non-immune cells in a TBK1-dependent and TBK1-independent manner, respectively.

Transient depletion of specific immune cell populations to improve adenovirus-mediated transgene expression in the liver

BACKGROUND & AIMS

Adenoviral (Ad) vectors are currently one of the most efficient tools for in vivo gene transfer to the liver. However, anti-Ad immune responses limit the safety and efficacy of these vectors. The initial inflammatory reaction is a concern in terms of toxicity, and it favours the development of cellular and humoral responses leading to short transgene persistence and inefficient vector re-administrations. Therefore, safe and simple ways to interfere with these processes are needed. Study ways to deplete specific immune cell populations and their impact on liver-directed gene transfer.

METHODS

First-generation Ad vectors encoding reporter genes (luciferase or β-galactosidase) were injected intravenously into Balb/c mice. Kupffer cells and splenic macrophages were depleted by intravenous administration of clodronate liposomes. B lymphocytes, CD4(+) , CD8(+) T lymphocytes or NK cells were depleted by intraperitoneal injection of anti-M plus anti-D, anti-CD4, anti-CD8 or anti-asialo-GM1 antibodies respectively. Long-term evolution of luciferase expression in the liver was monitored by bioluminescence imaging.

RESULTS

The anti-CD4 monoclonal antibody impaired cellular and humoral immune responses, leading to efficient vector re-administration. Clodronate liposomes had no impact on humoral responses but caused a 100-1000 fold increase in liver transduction, stabilized transgene expression, reduced the concentration of inflammatory cytokines, and inhibited lymphocyte activation.

CONCLUSIONS

Transient CD4(+) T-cell depletion using antibodies is a clinically feasible procedure that allows efficient Ad redosing. Systemic administration of clodronate liposomes may further increase the safety and efficacy of vectors.

Chronic HCV infection affects the NK cell phenotype in the blood more than in the liver

Although epidemiological and functional studies have implicated NK cells in protection and early clearance of HCV, the mechanism by which they may contribute to viral control is poorly understood, particularly at the site of infection, the liver. We hypothesized that a unique immunophenotypic/functional NK cell signature exists in the liver that may provide insights into the contribution of NK cells to viral control. Intrahepatic and blood NK cells were profiled from chronically infected HCV-positive and HCV-negative individuals. Baseline expression of activating and inhibitory receptors was assessed, as well as functional responses following stimulation through classic NK cell pathways. Independent of HCV infection, the liver was enriched for the immunoregulatory CD56^bright NK cell population, which produced less IFNγ and CD107a but comparable levels of MIP1β, and was immunophenotypically distinct from their blood counterparts. This profile was mostly unaltered in chronic HCV infection, though different expression levels of NKp46 and NKG2D were associated with different grades of fibrosis. In contrast to the liver, chronic HCV infection associated with an enrichment of CD161^lowperforin^high NK cells in the blood correlated with increased AST and 2B4 expression. However, the association of relatively discrete changes in the NK cell phenotype in the liver with the fibrosis stage nevertheless suggests an important role for the NK response. Overall these data suggest that tissue localization has a more pervasive effect on NK cells than the presence of chronic viral infection, during which these cells might be mostly attuned to limiting immunopathology. It will be important to characterize NK cells during early HCV infection, when they should have a critical role in limiting infection.

Longitudinal requirement for CD4+ T cell help for adenovirus vector-elicited CD8+ T cell responses

Despite the widespread use of replication-incompetent recombinant adenovirus (Ad) vectors as candidate vaccine platforms, the mechanism by which these vectors elicit CD8(+) T cell responses remains poorly understood. Our data demonstrate that induction and maintenance of CD8(+) T cell responses by Ad vector immunization is longitudinally dependent on CD4(+) T cell help for a prolonged period. Depletion of CD4(+) T cells in wild type mice within the first 8 d following Ad immunization resulted in dramatically reduced induction of Ag-specific CD8(+) T cells, decreased T-bet and eomesodermin expression, impaired KLRG1(+) effector differentiation, and atypical expression of the memory markers CD127, CD27, and CD62L. Moreover, these CD8(+) T cells failed to protect against a lethal recombinant Listeria monocytogenes challenge. Depletion of CD4(+) T cells between weeks 1 and 4 following immunization resulted in increased contraction of memory CD8(+) T cells. These data demonstrate a prolonged temporal requirement for CD4(+) T cell help for vaccine-elicited CD8(+) T cell responses in mice. These findings have important implications in the design of vaccines aimed at eliciting CD8(+) T cell responses and may provide insight into the impaired immunogenicity of vaccines in the context of AIDS and other CD4(+) T cell immune deficiencies.

CD4+ T cells play a critical role in the generation of primary and memory antitumor immune responses elicited by SA-4-1BBL and TAA-based vaccines in mouse tumor models

The role of CD4⁺ T cells in the generation of therapeutic primary and memory immune responses in cancer diverse immunotherapy settings remains ambiguous. We herein investigated this issue using two vaccine formulations containing a novel costimulatory molecule, SA-4-1BBL, as adjuvant and HPV E7 or survivin (SVN) as tumor associated antigens (TAAs) in two mouse transplantable tumor models; the TC-1 cervical cancer expressing xenogeneic HPV E7 and 3LL lung carcinoma overexpressing autologous SVN. Single vaccination with optimized SA-4-1BBL/TAA formulations resulted in the eradication of 6-day established TC-1 and 3LL tumors in >70% of mice in both models. The in vivo depletion of CD4⁺ T cells one day before tumor challenge resulted in compromised vaccine efficacy in both TC-1 (25%) and 3LL (12.5%) tumor models. In marked contrast, depletion of CD4⁺ T cells 5 days post-tumor challenge and one day prior to vaccination did not significantly alter the therapeutic efficacy of these vaccines. However, long-term immunological memory was compromised in the 3LL, but not in TC-1 model as a significant number (85.7%) of tumor free-mice succumbed to tumor growth when rechallenged with 3LL cells 60 days after the initial tumor inoculation. Collectively, these results demonstrate the indispensable role CD4⁺ T cells play in the generation of therapeutic primary immune responses elicited by SA-4-1BBL/TAA-based vaccines irrespective of the nature of TAAs and establish the importance of CD4⁺ T cells for long-term immune memory against 3LL tumor expressing self-antigen SVN, but not TC-1 expressing xenogeneic viral antigen E7.

Modeling pre-existing immunity to adenovirus in rodents: immunological requirements for successful development of a recombinant adenovirus serotype 5-based ebola vaccine

Pre-existing immunity (PEI) to human adenovirus serotype 5 (Ad5) worldwide is the primary limitation to routine clinical use of Ad5-based vectors in immunization platforms. Using systemic and mucosal PEI induction models in rodents (mice and guinea pigs), we assessed the influence of PEI on the type of adaptive immune response elicited by an Ad5-based vaccine for Ebola with respect to immunization route. Splenocytes isolated from vaccinated animals revealed that immunization by the same route in which PEI was induced significantly compromised Ebola Zaire glycoprotein (ZGP)-specific IFN-γ+ CD8+ T cells and ZGP-specific multifunctional CD8+ T cell populations. ZGP-specific IgG1 antibody levels were also significantly reduced and a sharp increase in serum anti-Ad5 neutralizing antibody (NAB) titers were noted following immunization. These immune parameters correlated with poor survival after lethal challenge with rodent-adapted Ebola Zaire virus (ZEBOV). Although the number of IFN-γ+ CD8+ T cells was reduced in animals given the vaccine by a different route from that used for PEI induction, the multifunctional CD8+ T cell response was not compromised. Survival rates in these groups were higher than when PEI was induced by the same route as immunization. These results suggest that antigen-specific multifunctional CD8(+) T cell and Th2 type antibody responses compromised by PEI to Ad5 are required for protection from Ebola. They also illustrate that methods for induction of PEI used in preclinical studies must be carefully evaluated for successful development of novel Ad5-based vaccines.

Adenoviral Vectors for Hemophilia Gene Therapy

Hemophilia is an inherited blood clotting disorder resulting from deficiency of blood coagulation factors. Current standard of care for hemophilia patients is frequent intravenous infusions of the missing coagulation factor. Gene therapy for hemophilia involves the introduction of a normal copy of the deficient coagulation factor gene thereby potentially offering a definitive cure for the bleeding disorder. A variety of approaches have been pursued for hemophilia gene therapy and this review article focuses on those that use adenoviral vectors.

Immune regulation and evasion of Mammalian host cell immunity during viral infection

The mammalian host immune system has wide array of defence mechanisms against viral infections. Depending on host immunity and the extent of viral persistence, either the host immune cells might clear/restrict the viral load and disease progression or the virus might evade host immunity by down regulating host immune effector response(s). Viral antigen processing and presentation in the host cells through major histocompatibility complex (MHC) elicit subsequent anti-viral effector T cell response(s). However, modulation of such response(s) might generate one of the important viral immune evasion strategies. Viral peptides are mostly generated by proteolytic cleavage in the cytosol of the infected host cells. CD8(+) T lymphocytes play critical role in the detection of viral infection by recognizing these peptides displayed at the plasma membrane by MHC-I molecules. The present review summarises the current knowledge on the regulation of mammalian host innate and adaptive immune components, which are operative in defence mechanisms against viral infections and the variety of strategies that viruses have evolved to escape host cell immunity. The understanding of viral immune evasion strategies is important for designing anti-viral immunotherapies.

Influenza A(H1N1)pdm09 virus suppresses RIG-I initiated innate antiviral responses in the human lung

Influenza infection is a major cause of morbidity and mortality. Retinoic acid-inducible gene I (RIG-I) is believed to play an important role in the recognition of, and response to, influenza virus and other RNA viruses. Our study focuses on the hypothesis that pandemic H1N1/09 influenza virus alters the influenza-induced proinflammatory response and suppresses host antiviral activity. We first compared the innate response to a clinical isolate of influenza A(H1N1)pdm09 virus, OK/09, a clinical isolate of seasonal H3N2 virus, OK/06, and to a laboratory adapted seasonal H1N1 virus, PR8, using a unique human lung organ culture model. Exposure of human lung tissue to either pandemic or seasonal influenza virus resulted in infection and replication in alveolar epithelial cells. Pandemic virus induces a diminished RIG-I mRNA and antiviral cytokine response than seasonal virus in human lung. The suppression of antiviral response and RIG-I mRNA expression was confirmed at the protein level by ELISA and western blot. We performed a time course of RIG-I and interferon-β (IFN-β) mRNA induction by the two viruses. RIG-I and IFN-β induction by OK/09 was of lower amplitude and shorter duration than that caused by PR8. In contrast, the pandemic virus OK/09 caused similar induction of proinflammatory cytokines, IL-8 and IL-6, at both the transcriptional and translational level as PR8 in human lung. Differential antiviral responses did not appear to be due to a difference in cellular infectivity as immunohistochemistry showed that both viruses infected alveolar macrophages and epithelial cells. These findings show that influenza A(H1N1)pdm09 virus suppresses anti-viral immune responses in infected human lung through inhibition of viral-mediated induction of the pattern recognition receptor, RIG-I, though proinflammatory cytokine induction was unaltered. This immunosuppression of the host antiviral response by pandemic virus may have contributed to the more serious lung infections that occurred in the H1N1 pandemic of 2009.

CD154 and IL-2 signaling of CD4+ T cells play a critical role in multiple phases of CD8+ CTL responses following adenovirus vaccination

Adenoviral (AdV) vectors represent most commonly utilized viral vaccines in clinical studies. While the role of CD8⁺ cytotoxic T lymphocyte (CTL) responses in mediating AdV-induced protection is well understood, the involvement of CD4⁺ T cell-provided signals in the development of functional CD8⁺ CTL responses remain unclear. To explore CD4⁺ T helper signals required for AdVova-stimulated CTL responses, we established an adoptive transfer system by transferring CD4⁺ T cells derived from various knock out and transgenic mice into wild-type and/or CD4-deficient animals, followed by immunizing with recombinant ovalbumin (OVA)-expressing AdVova vector. Without CD4⁺ T help, both primary and memory CTL responses were greatly reduced in this model, and were associated with increased PD-1 expression. The provision of OVA-specific CD4⁺ T help in CD4⁺ T cell-deficient mice restored AdVova-induced primary CTL responses, and supported survival and recall responses of AdVova-stimulated memory CTLs. These effects were specifically mediated by CD4⁺ T cell-produced IL-2 and CD154 signals. Adoptive transfer of “helped” or “unhelped” effector and memory CTLs into naïve CD4⁺ T cell-deficient or -sufficient mice also revealed an additional role for polyclonal CD4⁺ T cell environment in the survival of AdVova-stimulated CTLs, partially explaining the extension of CTL contraction phase. Finally, during recall responses, CD4⁺ T cell environment, particularly involving memory CD4⁺ T cells, greatly enhanced expansion of memory CTLs. Collectively, our data strongly suggest a critical role for CD4⁺ T help in multiple phases of AdV-stimulated CTL responses, and could partially explain certain failures in AdV-based immunization trials targeting malignant tumors and chronic diseases that are often associated with compromised CD4⁺ T cell population and function.

Gene transfection of multicellular spheroid of hepatocytes on an artificial substrate

The handling of hepatocytes, a major cell population in the liver, is an important technique in both liver tissue engineering and hepatology. However, these cells are so fragile that it has been impossible to harvest hepatocytes with high viability from tissue culture dishes after a period of culture in vitro. In this study, we employed an artificial substrate for transfection of multilayer hepatocytes and harvested these cells with high viability after transfection. Hepatocytes cultured on an amphiphilic artificial substrate form multilayer aggregates (spheroids) in the presence of growth factors during gene transfection with cation liposomes. Compared to cells cultured on a collagen-coated plate, these spheroids are easily harvested with high viability by pipetting in EDTA solution. In addition, these spheroids rapidly spread on collagen after transfer from the artificial substrate, demonstrating that hepatocytes in the center of the spheroids were viable. Epidermal growth factor (EGF) increased the transfection efficiency into hepatocytes while hepatocyte growth factor (HGF) alone did not increase the efficiency. However, HGF synergestically increased the effect of EGF on transfection. Interestingly, this transfection required the process of spheroid formation because the gene was not transfected once the spheroid formation completed or under conditions where hepatocytes did not form spheroids. This method using spheroidal hepatocytes for in vitro transfection is promising for the development of ex vivo gene therapy.

Resolution of immune response by recombinant transforming growth factor-beta (rTGF-β) during influenza A virus infection

BACKGROUND & OBJECTIVES

Replication of influenza A virus in the respiratory tract leads to cell damage and liberation of cytokines and chemokines. The in vivo cytokine induction and modulation by recombinant transforming growth factor- β1 (rTGF-β1) has not been studied. Therefore, in the present study the effect of rTGF-β1, a potent immunomodulatory cytokine which has anti-inflammatory properties and downregulates the release of inflammatory molecules, against influenza-virus infection in the airway of mice was investigated.

METHODS

rTGF-β1 was administered intravenously to mice with concomitant intranasal infection of influenza A/Udorn/317/72 (H3N2) virus, and the survival rate, virus titre, histopathological changes and levels of factors regulating inflammation in the airway fluid were analysed.

RESULT

The immune response to influenza A virus was characterized by an influx of both macrophages and lymphocytes into the lungs of the infected host. rTGF-β1 significantly suppressed virus multiplication and improved the survival rate of mice. rTGF-β1 downregulated infiltration of neutrophils and the release of inflammatory molecules, such as interferon-gamma (IFN-γ), interleukin-1 β (IL-1β) and stimulated release of IL-10 that potentiates anti-inflammatory response into airway.

INTERPRETATION & CONCLUSIONS

A generalized pulmonary inflammation does not contribute to viral clearance but represents an immunological background within which antiviral immunity operates. Treatment with rTGF-β1 reduced macrophage count and neutrophils influx in lungs of infected mice.

Yes-associated protein regulates the hepatic response after bile duct ligation

Human chronic cholestatic liver diseases are characterized by cholangiocyte proliferation, hepatocyte injury, and fibrosis. Yes-associated protein (YAP), the effector of the Hippo tumor-suppressor pathway, has been shown to play a critical role in promoting cholangiocyte and hepatocyte proliferation and survival during embryonic liver development and hepatocellular carcinogenesis. Therefore, the aim of this study was to examine whether YAP participates in the regenerative response after cholestatic injury. First, we examined human liver tissue from patients with chronic cholestasis. We found more-active nuclear YAP in the bile ductular reactions of primary sclerosing cholangitis and primary biliary cirrhosis patient liver samples. Next, we used the murine bile duct ligation (BDL) model to induce cholestatic liver injury. We found significant changes in YAP activity after BDL in wild-type mice. The function of YAP in the hepatic response after BDL was further evaluated with liver-specific Yap conditional deletion in mice. Ablating Yap in the mouse liver not only compromised bile duct proliferation, but also enhanced hepatocyte necrosis and suppressed hepatocyte proliferation after BDL. Furthermore, primary hepatocytes and cholangiocytes isolated from Yap-deficient livers showed reduced proliferation in response to epidermal growth factor in vitro. Finally, we demonstrated that YAP likely mediates its biological effects through the modulation of Survivin expression.

CONCLUSION

Our data suggest that YAP promotes cholangiocyte and hepatocyte proliferation and prevents parenchymal damage after cholestatic injury in mice and thus may mediate the response to cholestasis-induced human liver disease.

Requirement of CD4 help for induction of CD8 T cell response specific for virally derived h60

CD40-CD40L-mediated help from CD4 T cells is essential to induce primary CD8 T cell responses specific to the non-inflammatory cell-based antigen H60. In this study, using H60 as a model antigen, we generated recombinant vaccinia viruses (rVVs) expressing the H60 CD8 epitope and investigated whether CD4 help was required to activate the CD8 T cell response specific to the virally expressed H60. The immune response after infection with rVVs expressing H60 was similar to that after immunization with H60 congenic splenocytes, with a peak frequency of H60-specific CD8 T cells detected in the blood on day 10 post-infection. A CD8 T cell response specific for virally derived H60 was not induced in CD4-depleted mice, but was in CD40-deficient mice. These results provide insights into the characterization of the CD8 T cell response specifically for antigens originating from cellular sources compared to viral sources.

From crucial to negligible: functional CD8⁺ T-cell responses and their dependence on CD4⁺ T-cell help

CD8(+) T cells play an important role in controlling pathogenic infections and are therefore key players in the immune response. It has been shown that among other factors CD4(+) T cells can shape the magnitude as well as the quality of primary and/or secondary CD8(+) T-cell responses. However, due to the complexity and the differences among diverse immunization or infection models, the overall requirement, the time points, as well as the specific mechanism(s) of CD4(+) T-cell help may differ substantially. Here, we summarize current knowledge about the differential requirement of CD4(+) T-cell help in promoting primary CD8(+) T-cell responses as well as establishing functional memory CD8(+) T cells in various experimental settings.

Biodistribution and inflammatory profiles of novel penton and hexon double-mutant serotype 5 adenoviruses

The use of adenovirus serotype 5 (Ad5) vectors in the clinical setting is severely hampered by the profound liver tropism observed after intravascular delivery coupled with the pronounced inflammatory and innate immune response elicited by these vectors. Liver transduction by circulating Ad5 virions is mediated by a high-affinity interaction between the capsid hexon protein and blood coagulation factor X (FX), whilst penton–α_vintegrin interactions are thought to contribute to the induction of anti-Ad5 inflammatory and innate immune responses. To overcome these limitations, we sought to develop and characterise for the first time novel Ad5 vectors possessing mutations ablating both hexon:FX and penton:integrin interactions. As expected, intravascular administration of the FX binding-ablated Ad5HVR5*HVR7*E451Q vector (AdT*) resulted in significantly reduced liver transduction in vivo compared to Ad5. In macrophage-depleted mice, increased spleen uptake of AdT* was accompanied by an elevation in the levels of several inflammatory mediators. However ablation of the penton RGD motif in the AdT* vector background (AdT*RGE) resulted in a significant 5-fold reduction in spleen uptake and attenuated the antiviral inflammatory response. A reduction in spleen uptake and inflammatory activation was also observed in animals after intravascular administration of Ad5RGE compared to the parental Ad5 vector, with reduced co-localisation of the viral beta-galactosidase transgene with MAdCAM-1 + sinus-lining endothelial cells. Our detailed assessment of these novel adenoviruses indicates that penton base RGE mutation in combination with FX binding-ablation may be a viable strategy to attenuate the undesired liver uptake and pro-inflammatory responses to Ad5 vectors after intravascular delivery.

Capsid-specific T-cell responses to natural infections with adeno-associated viruses in humans differ from those of nonhuman primates

Hepatic adeno-associated virus serotype 2 (AAV2)-mediated gene transfer failed to achieve sustained transgene product expression in human subjects. We formulated the hypothesis that rejection of AAV-transduced hepatocytes is caused by AAV capsid-specific CD8(+) T cells that become reactivated upon gene transfer. Although this hypothesis was compatible with clinical data, which showed a rise in circulating AAV capsid-specific T cells following injection of AAV vectors, it did not explain that AAV vectors achieved long-term transgene expression in rhesus macaques, which are naturally infected with AAV serotypes closely related to those of humans. To address this apparent contradiction, we tested human and rhesus macaque samples for AAV capsid-specific T cells by intracellular cytokine staining combined with staining for T-cell subset and differentiation markers. This highly sensitive method, which could provide a tool to monitor adverse T-cell responses in gene transfer trials, showed that AAV capsid-specific CD8(+) and CD4(+) T cells can be detected in blood of naturally infected humans and rhesus macaques. They are present at higher frequencies in rhesus macaques. Furthermore, T cells from humans and rhesus macaques exhibit striking differences in their differentiation status and in their functions, which may explain the disparate duration of AAV-mediated gene transfer in these two species.

Adenovirus Vector-Derived VA-RNA-Mediated Innate Immune Responses

The major limitation of the clinical use of replication-incompetent adenovirus (Ad) vectors is the interference by innate immune responses, including induction of inflammatory cytokines and interferons (IFN), following in vivo application of Ad vectors. Ad vector-induced production of inflammatory cytokines and IFNs also results in severe organ damage and efficient induction of acquired immune responses against Ad proteins and transgene products. Ad vector-induced innate immune responses are triggered by the recognition of Ad components by pattern recognition receptors (PRRs). In order to reduce the side effects by Ad vector-induced innate immune responses and to develop safer Ad vectors, it is crucial to clarify which PRRs and which Ad components are involved in Ad vector-induced innate immune responses. Our group previously demonstrated that myeloid differentiating factor 88 (MyD88) and toll-like receptor 9 (TLR9) play crucial roles in the Ad vector-induced inflammatory cytokine production in mouse bone marrow-derived dendritic cells. Furthermore, our group recently found that virus associated-RNAs (VA-RNAs), which are about 160 nucleotide-long non-coding small RNAs encoded in the Ad genome, are involved in IFN production through the IFN-β promoter stimulator-1 (IPS-1)-mediated signaling pathway following Ad vector transduction. The aim of this review is to highlight the Ad vector-induced innate immune responses following transduction, especially VA-RNA-mediated innate immune responses. Our findings on the mechanism of Ad vector-induced innate immune responses should make an important contribution to the development of safer Ad vectors, such as an Ad vector lacking expression of VA-RNAs.

Quantitative analysis of the leaky expression of adenovirus genes in cells transduced with a replication-incompetent adenovirus vector

Theoretically, adenovirus (Ad) genes should not be expressed following transduction with a replication-incompetent Ad vector because the E1A gene, which is essential for the expression of other viral gene, is deleted in a replication-incompetent Ad vector. However, leaky expression of viral genes is known to occur following transduction with an E1-deleted Ad vector, leading to an induction of cellular immunity against Ad proteins. To date, no detailed analysis of the leaky expression profiles of Ad genes has been performed. In this study, we systematically examined the expression profiles of Ad genes in cells following transduction with a replication-incompetent Ad vector (Ad-L2) at multiplicities of infection (MOIs) of 10 and 100 using real-time RT-PCR. Significant expression was found for the E4 and pIX genes following transduction with Ad-L2 in cultured cells. The expression levels of the E4 and pIX genes were approximately 30- to 600-fold lower than those of the transgene (firefly luciferase), and 50- to 5000-fold lower than those of the E4 and pIX genes following transduction at the same MOI with the wild-type Ad. Unexpectedly, expression levels of the major capsid proteins were approximately the same as, or even slightly above, the background levels (Ad gene expression levels in mock-transduced cells). This study provides valuable information for the design of a safe and efficient replication-incompetent Ad vector.

MyD88-dependent protective immunity elicited by adenovirus 5 expressing the surface antigen 1 from Toxoplasma gondii is mediated by CD8(+) T lymphocytes

Toxoplasma gondii is an intracellular parasite widely spread around the world. The surface antigens (SAG) 1, 2 and 3 are the main proteins expressed on the surface of T. gondii tachyzoites. Replication-defective adenovirus serotype 5 (rAd5) is one of the most potent recombinant viral vectors for eliciting T cell-mediated immunity in mice and humans. Here we show that vaccination with rAd5 expressing SAG1 (AdSAG1), but neither SAG2 nor SAG3, induces protective immunity in the highly susceptible C57BL/6 mice challenged with T. gondii. Furthermore, we evaluated different immunological components involved on viral induced protective immunity. We observed that host protection elicited by AdSAG1 is highly dependent on IL-12, IFN-γ and CD8(+) T lymphocytes. Importantly, the induction of protective immunity (T cell-derived IFN-γ) was also dependent on Myeloid Differentiation Factor 88 (MyD88), and thus, likely to involve Toll-like Receptors. We conclude that protective parasite specific-CD8(+) T cells are elicited by a mechanism that involves MyD88-dependent induction of IL-12.

Intrinsic IL-21 signaling is critical for CD8 T cell survival and memory formation in response to vaccinia viral infection

CD4 T cell help plays an important role in promoting CD8 T cell immunity to pathogens. In models of infection with vaccinia virus (VV) and Listeria monocytogenes, CD4 T cell help is critical for the survival of activated CD8 T cells during both the primary and memory recall responses. Still unclear, however, is how CD4 T cell help promotes CD8 T cell survival. In this study, we first showed that CD4 T cell help for the CD8 T cell response to VV infection was mediated by IL-21, a cytokine produced predominantly by activated CD4 T cells, and that direct action of IL-21 on CD8 T cells was critical for the VV-specific CD8 T cell response in vivo. We next demonstrated that this intrinsic IL-21 signaling was essential for the survival of activated CD8 T cells and the generation of long-lived memory cells. We further revealed that IL-21 promoted CD8 T cell survival in a mechanism dependent on activation of the STAT1 and STAT3 pathways and subsequent upregulation of the prosurvival molecules Bcl-2 and Bcl-x(L). These results identify a critical role for intrinsic IL-21 signaling in CD8 T cell responses to an acute viral infection in vivo and may help design effective vaccine strategies.

GMCSF-interleukin fusion cytokines induce novel immune effectors that can serve as biopharmaceuticals for treatment of autoimmunity and cancer

We created the GIFTs, fusions of granulocyte-colony macrophage-stimulating-factor with IL-2, or IL-15 or IL-21, in order to stimulate distinct, but complimentary elements of the immune response. We found that the physical coupling of two functionally distinct cytokines as a bifunctional hybrid allowed for synergistic bioactivity not seen by the simple combined use of parent components. Indeed, despite how these interleukins are pro-inflammatory cytokines that serve essential roles in the maturation of CD8(+) T cells and NK cells, the GIFTs were remarkably different from one another, with GIFT-2 and GIFT-21 promoting and GIFT-15 downregulating inflammation. The common denominator to the biochemistry of these fusokines was their ability to hijack the signalling machinery associated with common to their respective γ-chain interleukin receptors, radically altering the activation status of responding lymphomyeloid cells. By studying the GIFTs, we found that both secreted and cell surface factors presented by GIFT-activated lymphomyeloid cells were required to modulate the immune responses in murine models of multiple sclerosis and cancer. The ability of GIFTs to co-opt the normal signalling machinery of interleukin receptors leads to the acquisition of functional responder cell phenotypes unparalleled in nature. These novel properties provide opportunities to alter maladapted immune responses in health and disease.

Adenovirus-mediated gene transfer

Recombinant adenoviruses are attractive vectors for short-term expression in mouse liver and primary cell lines. Various versatile vector systems have been developed which can be used for the reliable production of recombinant adenoviruses. This protocol describes the entire process for the production of recombinant adenoviruses using the AdEasy system. This protocol will give a practical step-by-step description from the cloning of the gene of interest until the in vivo administration in mice. The entire process will take about 8 weeks to complete.

Helper-Dependent Adenoviral Vectors

Helper-dependent adenoviral vectors are devoid of all viral coding sequences, possess a large cloning capacity, and can efficiently transduce a wide variety of cell types from various species independent of the cell cycle to mediate long-term transgene expression without chronic toxicity. These non-integrating vectors hold tremendous potential for a variety of gene transfer and gene therapy applications. Here, we review the production technologies, applications, obstacles to clinical translation and their potential resolutions, and the future challenges and unanswered questions regarding this promising gene transfer technology.

Hyperactive sleeping beauty transposase enables persistent phenotypic correction in mice and a canine model for hemophilia B

Sleeping Beauty (SB) transposase enables somatic integration of exogenous DNA in mammalian cells, but potency as a gene transfer vector especially in large mammals has been lacking. Herein, we show that hyperactive transposase system delivered by high-capacity adenoviral vectors (HC-AdVs) can result in somatic integration of a canine factor IX (cFIX) expression-cassette in canine liver, facilitating stabilized transgene expression and persistent haemostatic correction of canine hemophilia B with negligible toxicity. We observed stabilized cFIX expression levels during rapid cell cycling in mice and phenotypic correction of the bleeding diathesis in hemophilia B dogs for up to 960 days. In contrast, systemic administration of an inactive transposase system resulted in rapid loss of transgene expression and transient phenotypic correction. Notably, in dogs a higher viral dose of the active SB transposase system resulted into transient phenotypic correction accompanied by transient increase of liver enzymes. Molecular analysis of liver samples revealed SB-mediated integration and provide evidence that transgene expression was derived mainly from integrated vector forms. Demonstrating that a viral vector system can deliver clinically relevant levels of a therapeutic protein in a large animal model of human disease paves a new path toward the possible cure of genetic diseases.

CD8+ T cell responses following replication-defective adenovirus serotype 5 immunization are dependent on CD11c+ dendritic cells but show redundancy in their requirement of TLR and nucleotide-binding oligomerization domain-like receptor signaling

Replication-defective adenovirus serotype 5 (rAd5) is the most potent recombinant vector for eliciting CD8 T cell responses in humans. In this study, the innate mechanisms that influence T cell responses following rAd5 immunization were assessed in mice. Using rAd5 expressing enhanced GFP (eGFP-rAd5), we show that rAd5 transfects CD11c(+) dendritic cells (DCs) in draining lymph nodes in vivo following s.c. or i.m. immunization. Among distinct DC subsets, eGFP expression was highest in CD11c(+)CD8(-)B220(-) with a lower frequency detected in CD11c(+)CD8(+)B220(-) and CD11c(+)B220(+) plasmacytoid DCs. CD11c(+) DCs but not CD11c(-) cells from mice immunized with rAd5 encoding the SIINFEKL peptide induced proliferation of naive OT-I CD8 T cells. Furthermore, CD11c(+)CD8(+)B220(-) was the most potent DC subset for eliciting naive OT-I CD8 T cell proliferation. Of note, mice with pre-existing immunity to rAd5 had a substantial decrease in eGFP expression in DCs, which was associated with approximately 2-fold decrease in Th1 and complete inhibition of CD8 responses. Thus, pre-existing rAd5 immunity has a greater influence on CD8 compared with CD4 T cell responses. In terms of how innate cytokines and signaling pathways influenced T cell immunity following rAd5 immunization, we show that the magnitude and quality of CD8 T cell responses are partially dependent on MyD88 but independent of IL-12, type I IFN, apoptosis-associated speck-like protein, nucleotide-binding oligomerization domain-like receptor protein 3, and IL-1. Taken together, these data demonstrate a critical role for CD11c(+) DCs for CD8 responses but striking redundancy for innate cytokines and signaling by TLR and nucleotide-binding oligomerization domain-like receptor pathways.

Regulation of the induction and function of cytotoxic T lymphocytes by natural killer T cell

Cytotoxic T lymphocytes (CTLs) play a crucial role in the infections and the antitumor immunity. Induction and activation of antigen-specific CTLs is an important strategy in immunotherapy for various diseases, and several researchers have focused on the modulation of CTL induction and function. Natural killer T (NKT) cells are an important focus area of researchers studying immunomodulatory responses to tumors and infectious diseases. CD1d-restricted NKT cells consist of type I NKT cells and type II NKT cells. α-galactosylceramide (α-GalCer)-activated type I NKT cells secrete both Th1 (e.g., IFN-γ) and Th2 cytokines, affect the expression of costimulatory molecules in immune cells, and regulate the host immune system. Type II NKT cells, however, are stimulated by sulfatide, a self-glycolipid derived from myelin, and play an immunosuppressive role in animal model of autoimmune diseases. CTL generation, activation, and suppression are strongly affected by activated type I and type II NKT cells. Thus, the regulation of these NKT cells leads to the modification of CTL function. CTLs contribute to antimicrobial responses, antitumor immune and autoimmune responses. Understanding the role of NKT cells in the regulation of CTL generation, activation, and suppression enable the development of novel treatment strategies for these diseases.

AAV vectors avoid inflammatory signals necessary to render transduced hepatocyte targets for destructive T cells

Studies in mice indicate that gene transfer to liver with vectors based on adeno-associated viruses (AAVs) is characterized by immunological tolerance to antigenic transgene products. Mechanisms to explain host nonresponsiveness have focused on aberrant T-cell responses. We propose a distinct mechanism for conferring tolerance to AAV-transduced hepatocytes that relates to diminished sensitivity of the target organ to T cell-mediated effects. T cells to beta-galactosidase (beta-gal) were adoptively transferred into RAG(-/-) mice expressing beta-gal in hepatocytes due to prior administration of either Ad or AAV vectors. Adoptive transfer was associated with extinction of LacZ expression in Ad-LacZ-transduced RAG(-/-) mice and had no effect on liver LacZ expression in AAV-LacZ-transduced RAG(-/-) mice. Systemic administration of TLR ligands lipopolysaccharide (LPS) and CpG at the time of adoptive transfer did lead to extinction of LacZ expression. Systemic TLR ligands were associated with upregulation of major histocompatibility complex (MHC) class I and the cell adhesion molecules ICAM and VCAM as was seen with Ad-LacZ alone. These data indicate that AAV transduction lacks the inflammatory signals necessary to render hepatocyte targets for cytotoxic T lymphocytes (CTLs). Underlying liver pathology may confound vector performance and should be considered in the design of clinical trials.

Quality of the transgene-specific CD8+ T cell response induced by adenoviral vector immunization is critically influenced by virus dose and route of vaccination

Adenoviral vectors have been widely used for experimental gene therapy and vaccination, yet there is a surprising lack of knowledge connecting the route and dose of adenovirus administration to the induced transgene-specific immune response. We have recently demonstrated polyfunctional CD8(+) T cells and protective memory responses using adenoviral vectors, which seem to contrast with recent reports suggesting that an exhausted CD8(+) T cell phenotype is induced by inoculation with adenoviral vectors. Accordingly, we investigated the route and dose interrelationship for transgene-specific CD8(+) T cells using adenoviral vectors encoding beta-galactosidase applied either s.c. or i.v. Irrespective of the route of inoculation, most of the adenoviral inoculum was found to disseminate systemically as the dose was raised beyond 10(9) particles. The number of transgene-specific CD8(+) T cells correlated positively with dissemination, whereas the functional capacity of the generated T cells correlated inversely with vector dissemination. A comparison of the immune response to s.c. or i.v. administration at moderate doses revealed that inoculation by both routes induced a transient peak of IFN-gamma-producing CD8(+) T cells 2 to 3 wk postinfection, but following i.v. administration, these cells were only detected in the liver. Two to four months after systemic, but not peripheral, immunization, dysfunctional transgene-specific CD8(+) T cells impaired in both cytokine production and important in vivo effector functions, accumulated in the spleen. These findings indicate that the localization of the adenoviral inoculum and not the total Ag load determines the quality of the CD8(+) T cell response induced with adenoviral vaccines.