Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2007 Oct;7(5):347-60.
doi: 10.2174/156652307782151498.

Immune responses to adenovirus and adeno-associated vectors used for gene therapy of brain diseases: the role of immunological synapses in understanding the cell biology of neuroimmune interactions

Pedro R Lowenstein  1 , Ronald J Mandel, Wei-Dong Xiong, Kurt Kroeger, Maria G Castro
Affiliations
Review

Immune responses to adenovirus and adeno-associated vectors used for gene therapy of brain diseases: the role of immunological synapses in understanding the cell biology of neuroimmune interactions

Pedro R Lowenstein et al. Curr Gene Ther. 2007 Oct.

Abstract

Researchers have conducted numerous pre-clinical and clinical gene transfer studies using recombinant viral vectors derived from a wide range of pathogenic viruses such as adenovirus, adeno-associated virus, and lentivirus. As viral vectors are derived from pathogenic viruses, they have an inherent ability to induce a vector specific immune response when used in vivo. The role of the immune response against the viral vector has been implicated in the inconsistent and unpredictable translation of pre-clinical success into therapeutic efficacy in human clinical trials using gene therapy to treat neurological disorders. Herein we thoroughly examine the effects of the innate and adaptive immune responses on therapeutic gene expression mediated by adenoviral, AAV, and lentiviral vectors systems in both pre-clinical and clinical experiments. Furthermore, the immune responses against gene therapy vectors and the resulting loss of therapeutic gene expression are examined in the context of the architecture and neuroanatomy of the brain immune system. The chapter closes with a discussion of the relationship between the elimination of transgene expression and the in vivo immunological synapses between immune cells and target virally infected brain cells. Importantly, although systemic immune responses against viral vectors injected systemically has thought to be deleterious in a number of trials, results from brain gene therapy clinical trials do not support this general conclusion suggesting brain gene therapy may be safer from an immunological standpoint.

PubMed Disclaimer

Figures

Fig. (1)
Fig. (1). Anti-adenoviral immune responses completely eliminate transgene expression from first generation adenoviral vectors
A. The levels of transgene expression and MHC presentation of viral epitopes in animals injected with a first generation adenoviral vector into the CNS are illustrated. MHC-I presentation of viral epitopes peaks earlier due to intracellular degredation and presentation of capsid derived epitopes. Transgene expression (and consequent MHC antigen presentation) are completely abrogated following systemic immunization with adenovirus. B. Immunoreactivity for β-galactosidase illustrates the effects of a systemic immune response against adenovirus on transgene expression from first generation adenoviral vectors in the brain of rats immunized against inactivated adenovirus (top panels) or adenovirus (bottom panels). Short term (21 days post immunization, left panels) and medium term (60 days post immunization, right panels) expression of β-gal is shown. Note the sharp reduction of β-gal immunoreactivity in immunized animals compared to controls animals immunized with inactivated adenovirus. Sixty days later, transgene expression is completely eliminated in immunized animals while transgene expression is sustained in control immunized animals. C. A schematic of first generation vector infection, uncoating, nuclear transduction, production of transgene and presentation of viral antigenic epitopes on MHC-I is shown shortly after and during vector infection. D. A schematic of the same cells is shown >30 days later. Note the continued expression of viral proteins from the first generation adenoviral vector genomes and their presentation by MHC molecules on the cell surface.
Fig. (2)
Fig. (2). Anti-adenoviral immune responses are incapable of eliminating transgene expression from HC-Ad vectors
A. The levels of transgene expression and MHC presentation of viral epitopes in animals injected with a HC-Ad vector into the CNS are illustrated. MHC presentation of viral protein is short-term because only capsid derived epitopes can be presented during capsid degredation. Transgene expression in the brain is sustained, even after systemic immunization against adenovirus. B. Immunoreactivity for β-galactosidase illustrates the failure of a systemic immune response against adenovirus to eliminate transgene expression from HC-Ad vectors in the brain of rats immunized against adenovirus (top panels) or saline alone (bottom panels). Short term (21 days post immunization, left panels) and medium-long term (60 days post immunization, right panels) expression of β-gal is shown. Note the sustained expression of β-gal in both Ad-immunized animals and controls animals immunized with saline alone at 14 and 60 days immunization. C. A schematic of HC-Ad vector infection, uncoating, nuclear transduction, production of transgene and presentation of viral antigenic epitopes on MHC-I is shown after vector infection. D. A schematic of the same cells is shown >30 days later. Note the absence of expression of viral proteins from the HC-Ad vector and the lack of presentation of viral epitopes by MHC molecules on the cell surface.
Fig. (3)
Fig. (3). Comparison of pre-existing responses against first generation adenovirus, high capacity adenovirus, and transgene
A. The levels of intracranial transgene expression in the presence of a pre-existing systemic anti-adenovirus immune response are shown. Note the sharp reduction of transgene expression following intracranial delivery of first generation adenovirus compared to HC-Ad transgene expression. B. First generation adenovirus and C. HC-Ad mediated transgene expression in the mouse brain is visualized by β-gal immunoreactivity at 21 days and one year post intracranial vector delivery. Note the sustained expression of β-gal from both vectors in control immunized animals and persistence of expression in animals injected with HC-Ad even at one year post vector injection compared to the complete ablation of transgene expression in animals injected with first generation adenoviral vectors. C. β-gal immunoreactivity in the brain of animals pre-immunized with saline (top panels) or with β-gal (bottom panels) is shown seven weeks post intracranial vector delivery. Right panels depict high magnification images of immuoreactive area. D. Quantitative stereology of β-gal immunocytochemistry reveals a statistically significant decrease in β-gal immunoreactivity in animals pre-immunized with β-gal when compared to animals immunized with saline alone.
Fig. (4)
Fig. (4). Pre-existing responses against AAV vectors
A. Intrastriatal GDNF expression as determined by ELISA (top panels) and immunohistochemistry (bottom panels). Immunization with wt AAV2 completely blocked GDNF expression at both the 2- and 4-week time points following rAAV2-GDNF striatal transduction.as evidenced the striatum by both ELISA and ICC when compared to naïve animals. Injection of rAAV2 in the right striatum completely blocked GDNF expression when AAV2-GDNF was readministered in the left striatum (bottom left panel). The bottom right panels shows a representative section from a naive animal 4 weeks after rAAV2-GDNF injection in right striatum, with no further treatment. B. Striatal sections were immunostained with for MHC-I (green) and CD8α (red) in animals injected with rAAV. Note the increase of CD8α immunoreactivity in the brains of animals that received a second injection (middle panel) as compared to those animals only receiving a single injection (left panel). The right panel is a higher magnification image of the middle panel.
Fig. (5)
Fig. (5). SMAC formation at immunological synapses in vivo, between T cells and infected astrocytes in the brain
Upper panels illustrate confocal images of: DAPI (blue), LFA-1 (red), TCR (green), and the virally infected cell (TK; in white) (Fig. 1A-F). Scale bars=15 μm. The yellow asterisk in F indicates the location of the T cell. Low (G) and high (H) magnifications of the synapse are illustrated. 3D reconstructed images (J) illustrate the characteristic structure of the p-SMAC (outer LFA-1 ring) and c-SMAC (inner TCR cluster) of the immunological synapse. The image shown in J was rotated so that the plane of the interface of the immunological synapse (broken arrow in 1H) could be observed from above (white arrow in H shows the angle of vision of the 3D reconstruction in J). I illustrates the intensity of fluorescence measured at the interface (yellow line in H) of the immunological synapse. The graph shows the relative intensity values of fluorescence of LFA-1 (in red) and TCR (in green), showing the expected distribution with more intense LFA-1 staining towards the outside p-SMAC, and stronger TCR in the c-SMAC. K is diagrammatic view of a T-cell contacting an infected astrocyte illustrating the localization of molecules involved in the immunological synapse as well as polarized phosphorylated tyrosine kinases. LFA-1 transduces signals to the cytoskeleton through talin, and binds to ICAM-1 on the target cells.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Ali S, King GD, Curtin JF, Candolfi M, Xiong W, Liu C, Puntel M, Cheng Q, Prieto J, Ribas A, Kupiec-Weglinski J, van Rooijen N, Lassmann H, Lowenstein PR, Castro MG. Combined immunostimulation and conditional cytotoxic gene therapy provide long-term survival in a large glioma model. Cancer Res. 2005;65(16):7194–7204. - PMC - PubMed
    1. Barcia C, Gerdes C, Xiong W, Thomas CE, Liu C, Kroeger KM, Castro MG, Lowenstein PR. Immunological thresholds in neurological gene therapy: highly efficient elimination of transduced cells may be related to the specific formation of immunological synapses between T cells and virus-infected brain cells. Neuron Glial. Biology. 2006a;2(4):309–327. - PMC - PubMed
    1. Barcia C, Thomas CE, Curtin JF, King GD, Wawrowsky K, Candolfi M, Xiong WD, Liu C, Kroeger K, Boyer O, Kupiec-Weglinski J, Klatzmann D, Castro MG, Lowenstein PR. In vivo mature immunological synapses forming SMACs mediate clearance of virally infected astrocytes from the brain. J. Exp. Med. 2006b;203(9):2095–2107. - PMC - PubMed
    1. Bechmann I, Galea I, Perry VH. What is the blood-brain barrier (not)? Trends Immunol. 2007;28(1):5–11. - PubMed
    1. Blacklow NR, Hoggan MD, Rowe WP. Serologic evidence for human infection with adenovirus-associated viruses. J. Natl. Cancer Inst. 1968;40(2):319–327. - PubMed

Publication types

MeSH terms