Highly efficient transduction of human plasmacytoid dendritic cells without phenotypic and functional maturation

<p>Abstract</p> <p>Background</p> <p>Gene modified dendritic cells (DC) are able to modulate DC functions and induce therapeutic immunity or tolerance in an antigen-specific manner. Among the different DC subsets, plasmacytoid DC (pDC) are well known for their ability to recognize and respond to a variety of viruses by secreting high levels of type I interferon.</p> <p>Methods</p> <p>We analyzed here, the transduction efficiency of a pDC cell line, GEN2.2, and of pDC derived from CD34+ progenitors, using lentiviral vectors (LV) pseudotyped with different envelope glycoproteins such as the vesicular stomatitis virus envelope (VSVG), the gibbon ape leukaemia virus envelope (GaLV) or the feline endogenous virus envelope (RD114). At the same time, we evaluated transgene expression (E-GFP reporter gene) under the control of different promoters.</p> <p>Results</p> <p>We found that efficient gene transfer into pDC can be achieved with VSVG-pseudotyped lentiviral vectors (LV) under the control of phoshoglycerate kinase (PGK) and elongation factor-1 (EF1α) promoters (28% to 90% of E-GFP⁺cells, respectively) in the absence of phenotypic and functional maturation. Surprisingly, promoters (desmin or synthetic C5–12) described as muscle-specific and which drive gene expression in single strand AAV vectors in gene therapy protocols were very highly active in pDC using VSVG-LV.</p> <p>Conclusion</p> <p>Taken together, our results indicate that LV vectors can serve to design pDC-based vaccines in humans, and they are also useful <it>in vitro </it>to evaluate the immunogenicity of the vector preparations, and the specificity and safety of given promoters used in gene therapy protocols.</p

Polymers for Improving the In Vivo Transduction Efficiency of AAV2 Vectors

Background: Adeno-associated virus has attracted great attention as vehicle for body-wide gene delivery. However, for the successful treatment of a disease such as Duchenne muscular dystrophy infusion of very large amounts of vectors is required. This not only raises questions about the technical feasibility of the large scale production but also about the overall safety of the approach. One way to overcome these problems would be to find strategies able to increase the in vivo efficiency. Methodology: Here, we investigated whether polymers can act as adjuvants to increase the in vivo efficiency of AAV2. Our strategy consisted in the pre-injection of polymers before intravenous administration of mice with AAV2 encoding a murine secreted alkaline phosphatase (mSeAP). The transgene expression, vector biodistribution and tissue transduction were studied by quantification of the mSeAP protein and real time PCR. The injection of polyinosinic acid and polylysine resulted in an increase of plasmatic mSeAP of 2- and 12-fold, respectively. Interestingly, polyinosinic acid pre-injection significantly reduced the neutralizing antibody titer raised against AAV2. Conclusions: Our results show that the pre-injection of polymers can improve the overall transduction efficiency of systemically administered AAV2 and reduce the humoral response against the capsid proteins

Major Subsets of Human Dendritic Cells Are Efficiently Transduced by Self-Complementary Adeno-Associated Virus Vectors 1 and 2▿

Dendritic cells (DC) are antigen-presenting cells pivotal for inducing immunity or tolerance. Gene transfer into DC is an important strategy for developing immunotherapeutic approaches against infectious pathogens and cancers. One of the vectors previously described for the transduction of human monocytes or DC is the recombinant adeno-associated virus (rAAV), with a genome conventionally packaged as a single-stranded (ss) molecule. Nevertheless, its use is limited by the poor and variable transduction efficiency of DC. In this study, AAV type 1 (AAV1) and AAV2 vectors, which expressed the enhanced green fluorescent protein and were packaged as ss or self-complementary (sc) duplex strands, were used to transduce different DC subsets generated ex vivo and the immunophenotypes, states of differentiation, and functions of the subsets were carefully examined. We show here for the first time that a single exposure of monocytes (Mo) or CD34+ progenitors (CD34) to sc rAAV1 or sc rAAV2 leads to high transduction levels (5 to 59%) of differentiated Mo-DC, Mo-Langerhans cells (LC), CD34-LC, or CD34-plasmacytoid DC (pDC), with no impact on their phenotypes and functional maturation of these cells, compared to those of exposure to ss rAAV. Moreover, we show that all these DC subpopulations can also be efficiently transduced after commitment to their differentiation pathways. Furthermore, these DC subsets transduced with sc rAAV1 expressing a tumor antigen were potent activators of a CD8+-T-cell clone. Altogether, these results show the high potential of sc AAV1 and sc AAV2 vectors to transduce ex vivo conventional DC, LC, or pDC or to directly target them in vivo for the design of new DC-based immunotherapies

Prevalence and long-term monitoring of humoral immunity against adeno-associated virus in Duchenne Muscular Dystrophy patients

International audienceAdeno-associated virus (AAV) vectors are promising candidates for gene therapy and have been explored as gene delivery vehicles in the treatment of Duchenne Muscular Dystrophy (DMD). Recent studies showed compelling evidence of therapeutic efficacy in large animal models following the intravenous delivery of AAV vectors expressing truncated forms of dystrophin. However, to translate these results to humans, careful assessment of the prevalence of anti-AAV neutralizing antibodies (NAbs) is needed, as presence of preexisting NABs to AAV in serum have been associated with a drastic diminution of vector transduction. Here we measured binding and neutralizing antibodies against AAV serotype 1, 2, and 8 in serum from children and young adults with DMD (n = 130). Results were compared with to age-matched healthy donors (HD, n = 113). Overall, approximately 54% of all subjects included in the study presented IgG to AAV2, 49% to AAV1, and 41% to AAV8. A mean of around 80% of IgG positive sera showed neutralizing activity with no statistical difference between DMD and HD. NAb titers for AAV2 were higher than AAV1, and AAV8 in both populations studied. Older DMD patients (13-24 years old) presented significantly lower anti-AAV8 IgG4 subclass. Anti-AAV antibodies were found to be decreased in DMD patients subjected to a 6-month course of corticosteroids and in subjects receiving a variety of immunosuppressive drugs including B cell targeting drugs. Longitudinal follow up of humoral responses to AAV over up to 6 years showed no change in antibody titers, suggesting that in this patient population, seroconversion is a rare event in humans

Capsid-specific removal of circulating antibodies to adeno-associated virus vectors

International audienceNeutralizing antibodies directed against adeno-associated virus (AAV) are commonly found in humans. In seropositive subjects, vector administration is not feasible as antibodies neutralize AAV vectors even at low titers. Consequently, a relatively large proportion of humans is excluded from enrollment in clinical trials and, similarly, vector redosing is not feasible because of development of high-titer antibodies following AAV vector administration. Plasmapheresis has been proposed as strategy to remove anti-AAV antibodies from the bloodstream. Although safe and relatively effective, the technology has some limitations mainly related to the nonspecific removal of all circulating IgG. Here we developed an AAV-specific plasmapheresis column which was shown to efficiently and selectively deplete anti-AAV antibodies without depleting the total immunoglobulin pool from plasma. We showed the nearly complete removal of anti-AAV antibodies from high titer purified human IgG pools and plasma samples, decreasing titers to levels that allow AAV vector administration in mice. These results provide proof-of-concept of a method for the AAV-specific depletion of neutralizing antibodies in the setting of in vivo gene transfer

Adeno-Associated Virus Vector (AAV) microdystrophin gene therapy prolongs survival and restores muscle function in the canine model of Duchenne Muscular Dystrophy (DMD)

Duchenne Muscular Dystrophy (DMD) is a X-linked inherited muscle-wasting disease primarily affecting young boys with a prevalence of 1:5,000. The disease is caused by loss-of-function mutations in the gene encoding for the Dystrophin protein and is characterized by systemic, progressive, irreversible and severe loss of muscle function. Among vector systems that allow efficient in vivo gene transfer, recombinant Adeno-Associated Virus vectors (rAAV) hold great promise and allow very efficient transduction of skeletal and cardiac muscles. However, full-length dystrophin cDNA exceeds the packaging capacity for a single rAAV gene-delivery cassette. Therefore, truncated versions namely micro-dystrophins have been designed and optimized to contain few clinically important regions of the dystrophin protein. We have tested a rAAV2/8 vector encoding a sequence optimised canine micro-dystrophin transgene, driven by a muscle-synthetic Spc512 promoter (rAAV2/8-Spc512-µDys) in a total of 12 Golden Retriever Muscular Dystrophy (GRMD) dogs, the canine model of DMD. Isolated limb perfusion studies using a single administration of vector induced high levels of micro-dystrophin expression in the treated limb (up to 90% dystrophin positive fibres) with significant normalisation of histological, NMR imaging and spectroscopy parameters and muscle strength, without deleterious immune responses. Similarly, single-dose intravascular delivery of the same rAAV2/8-Spc512-µDys, in absence of immunosuppression, led to long-term transduction of distant muscle groups and extended lifespan (up to 2 years). Profound improvement of multiple clinical features was observed, including gait and respiratory parameters and no toxicity or deleterious humoral and/or cell-mediated immune responses were observed. This study demonstrates the safety and long term efficacy of rAAV2/8-Spc5.12-µDys gene therapy in a relevant large-animal models of DMD and paves the way towards human clinical gene therapy using systemic peripheral vein administration of vector, and applicable to all DMD patients regardless of their genotype