Transduction of Dendritic Cells by DNA Viral Vectors Directs the Immune Response to Transgene Products in Muscle Fibers

Abstract

Immune responses to vector-corrected cells have limited the application of gene therapy for treatment of chronic disorders such as inherited deficiency states. We have found that recombinant adeno-associated virus (AAV) efficiently transduces muscle fibers in vivo without activation of cellular and humoral immunity to neoantigenic transgene products such as β-galactosidase, which differs from the experience with recombinant adenovirus, where vibrant T-cell responses to the transgene product destroy the targeted muscle fibers. T cells activated following intramuscular administration of adenovirus expressing lacZ (AdlacZ) can destroy AAVlacZ-transduced muscle fibers, indicating a prior state of immunologic nonresponsiveness in the context of AAV gene therapy. Adoptive transfer of dendritic cells infected with AdlacZleads to immune mediated elimination of AAVlacZ-transduced muscle fibers. AAVlacZ-transduced antigen-presenting cells fail to demonstrate β-galactosidase activity and are unable to elicit transgene immunity in adoptive transfer experiments. These studies indicate that vector-mediated transduction of dendritic cells is necessary for cellular immune responses to muscle gene therapy, a step which AAV avoids, providing a useful biological niche for its use in gene therapy.

Intradermal Immunization with rAAV1 Vector Induces Robust Memory CD8+ T Cell Responses Independently of Transgene Expression in DCs

“…A number of mechanisms have been considered so far to explain the limited induction of potent effector/memory CTLs following intramuscular immunization with rAAV vectors. This includes rAAV-intrinsic, poor DC transduction ability 14 and insufficient inflammatory responses leading to poor MHC class I upregulation on myocytes 16 and sustained transgene expression, 7,16 or transgene-intrinsic limitations, lack of potent MHC class II epitope in the construct. 7,8 Our results suggest that a combination of signals might be needed.…”

“…Beside transgene intrinsic factors, such as encoded MHC class II epitopes, the ability of a given rAAV serotype to efficiently transduce DCs in vivo, and thus lead to efficient direct presentation of the transgene product, has been brought forward as a key limiting factor for rAAV vectors in inducing potent CTL responses. [14][15][16][17] Underlying evidences for such a paradigm, however, have mostly been derived from intramuscular or intraperitoneal immunizations, and they might not fully reflect known differences in peripheral tissues' DC networks and potential to cross-present exogenous antigens. We thus next investigated the requirement for transgene expression in DCs for the induction of CD8 + T cell responses upon rAAV2/1 vector administration in the skin.…”

“…13 A key limitation of rAAV vectors in generating potent cytotoxic T cell (cytotoxic T lymphocyte [CTL]) responses to encoded transgenes notably resides in the limited triggering of local inflammation and poor transduction of antigen-presenting cells achieved by most common rAAV serotypes. [14][15][16][17] The latter most probably imposes an enhanced reliance on efficient cross-presentation of tissue-expressed transgene products by dendritic cells (DCs) for efficient T cell priming following rAAV-mediated vaccination.…”

The Role of the Adeno-Associated Virus Capsid in Gene Transfer

“…Therefore, the risk of integration is minimal, compared with retroviral vectors that require integration into the host genome and have the potential to activate proto-oncogenes. (5) Low immunogenicity: unlike adenoviral vectors, a robust T cell response to the vector is not generated by AAV [14], although humoral immune responses are generated, which may result in viral neutralization [15]. The use of other AAV serotypes may circumvent this response and allow for repeated treatments [16].…”

Standardized Xylocarpus moluccensis fruit fraction mitigates collagen-induced arthritis in mice by regulating immune response

“…The lymphocytes banded at the interface were collected, washed once and resuspended to a cell density of 10 6 cells/ml in RPMI with 10% FBS. [20] Cells were plated at a density of 5 9 10 4 per well in 24-well plate and stimulated with LPS (100 ng/ml), concanavalin A (5 lg/ml) and bovine type II collagen (20 lg/ml) in the presence of different doses of F018. Cell proliferation was measured after 72 h by MTT assay.…”