Publications by authors named "Grant J Logan"

22 Publications

  • Page 1 of 1

Gain-of-function factor H-related 5 protein impairs glomerular complement regulation resulting in kidney damage.

Proc Natl Acad Sci U S A 2021 Mar;118(13)

Centre for Inflammatory Disease, Imperial College London, London W12 0NN, United Kingdom;

Genetic variation within the factor H-related (FHR) genes is associated with the complement-mediated kidney disease, C3 glomerulopathy (C3G). There is no definitive treatment for C3G, and a significant proportion of patients develop end-stage renal disease. The prototypical example is CFHR5 nephropathy, through which an internal duplication within a single gene generates a mutant FHR5 protein (FHR5mut) that leads to accumulation of complement C3 within glomeruli. To elucidate how abnormal FHR proteins cause C3G, we modeled CFHR5 nephropathy in mice. Animals lacking the murine factor H (FH) and FHR proteins, but coexpressing human FH and FHR5mut (hFH-FHR5mut), developed glomerular C3 deposition, whereas mice coexpressing human FH with the normal FHR5 protein (hFH-FHR5) did not. Like in patients, the FHR5mut had a dominant gain-of-function effect, and when administered in hFH-FHR5 mice, it triggered C3 deposition. Importantly, adeno-associated virus vector-delivered homodimeric mini-FH, a molecule with superior surface C3 binding compared to FH, reduced glomerular C3 deposition in the presence of the FHR5mut. Our data demonstrate that FHR5mut causes C3G by disrupting the homeostatic regulation of complement within the kidney and is directly pathogenic in C3G. These results support the use of FH-derived molecules with enhanced C3 binding for treating C3G associated with abnormal FHR proteins. They also suggest that targeting FHR5 represents a way to treat complement-mediated kidney injury.
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http://dx.doi.org/10.1073/pnas.2022722118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8020653PMC
March 2021

Use of a Hybrid Adeno-Associated Viral Vector Transposon System to Deliver the Insulin Gene to Diabetic NOD Mice.

Cells 2020 10 2;9(10). Epub 2020 Oct 2.

School of Life Sciences, University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007, Australia.

Previously, we used a lentiviral vector to deliver furin-cleavable human insulin () to the livers in several animal models of diabetes using intervallic infusion in full flow occlusion (FFO), with resultant reversal of diabetes, restoration of glucose tolerance and pancreatic transdifferentiation (PT), due to the expression of beta (β)-cell transcription factors (β-TFs). The present study aimed to determine whether we could similarly reverse diabetes in the non-obese diabetic (NOD) mouse using an adeno-associated viral vector (AAV) to deliver - ± the β-TF to the livers of diabetic mice. The traditional AAV8, which provides episomal expression, and the hybrid AAV8/ that results in transgene integration were used. Diabetic mice that received AAV8- became hypoglycaemic with abnormal intraperitoneal glucose tolerance tests (IPGTTs). Expression of β-TFs was not detected in the livers. Reversal of diabetes was not achieved in mice that received AAV8--FUR and AAV8- and IPGTTs were abnormal. Normoglycaemia and glucose tolerance were achieved in mice that received AAV8/-/FFO. Definitive evidence of PT was not observed. This is the first in vivo study using the hybrid AAV8/ system to treat Type 1 diabetes (T1D). However, further development is required before the system can be used for gene therapy of T1D.
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http://dx.doi.org/10.3390/cells9102227DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600325PMC
October 2020

Restoring the natural tropism of AAV2 vectors for human liver.

Sci Transl Med 2020 09;12(560)

Translational Vectorology Research Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead, NSW 2145, Australia.

Recent clinical successes in gene therapy applications have intensified interest in using adeno-associated viruses (AAVs) as vectors for therapeutic gene delivery. Although prototypical AAV2 shows robust in vitro transduction of human hepatocyte-derived cell lines, it has not translated into an effective vector for liver-directed gene therapy in vivo. This is consistent with observations made in (FRG) mice with humanized livers, showing that AAV2 functions poorly in this xenograft model. Here, we derived naturally hepatotropic AAV capsid sequences from primary human liver samples. We demonstrated that capsid mutations, likely acquired as an unintentional consequence of tissue culture propagation, attenuated the intrinsic human hepatic tropism of natural AAV2 and related human liver AAV isolates. These mutations resulted in amino acid changes that increased binding to heparan sulfate proteoglycan (HSPG), which has been regarded as the primary cellular receptor mediating AAV2 infection of human hepatocytes. Propagation of natural AAV variants in vitro showed tissue culture adaptation with resulting loss of tropism for human hepatocytes. In vivo readaptation of the prototypical AAV2 in FRG mice with a humanized liver resulted in restoration of the intrinsic hepatic tropism of AAV2 through decreased binding to HSPG. Our results challenge the notion that high affinity for HSPG is essential for AAV2 entry into human hepatocytes and suggest that natural AAV capsids of human liver origin are likely to be more effective for liver-targeted gene therapy applications than culture-adapted AAV2.
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http://dx.doi.org/10.1126/scitranslmed.aba3312DOI Listing
September 2020

Efficient editing of OTC-deficient patient-derived primary human hepatocytes.

JHEP Rep 2020 Feb 27;2(1):100065. Epub 2019 Dec 27.

Gene Therapy Research Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney and Sydney Children's Hospitals Network, Westmead, Australia.

Background & Aims: Genome editing technology has immense therapeutic potential and is likely to rapidly supplant contemporary gene addition approaches. Key advantages include the capacity to directly repair mutant loci with resultant recovery of physiological gene expression and maintenance of durable therapeutic effects in replicating cells. In this study, we aimed to repair a disease-causing point mutation in the ornithine transcarbamylase () locus in patient-derived primary human hepatocytes at therapeutically relevant levels.

Methods: Editing reagents for precise CRISPR/SaCas9-mediated cleavage and homology-directed repair (HDR) of the human locus were first evaluated against an minigene cassette transposed into the mouse liver. The editing efficacy of these reagents was then tested on the native locus in patient-derived primary human hepatocytes xenografted into the FRG ( ) mouse liver. A highly human hepatotropic capsid (NP59) was used for adeno-associated virus (AAV)-mediated gene transfer. Editing events were characterised using next-generation sequencing and restoration of OTC expression was evaluated using immunofluorescence.

Results: Following AAV-mediated delivery of editing reagents to patient-derived primary human hepatocytes , locus-specific cleavage was achieved at efficiencies of up to 72%. Importantly, successful editing was observed in up to 29% of alleles at clinically relevant vector doses. No off-target editing events were observed at the top 10 -predicted sites in the genome.

Conclusions: We report efficient single-nucleotide correction of a disease-causing mutation in the locus in patient-derived primary human hepatocytes at levels that, if recapitulated in the clinic, would provide benefit for even the most therapeutically challenging liver disorders. Key challenges for clinical translation include the cell cycle dependence of classical HDR and mitigation of unintended on- and off-target editing events.

Lay Summary: The ability to efficiently and safely correct disease-causing mutations remains the holy grail of gene therapy. Herein, we demonstrate, for the first time, efficient correction of a patient-specific disease-causing mutation in the gene in primary human hepatocytes, using therapeutically relevant vector doses. We also highlight the challenges that need to be overcome for this technology to be translated into clinical practice.
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http://dx.doi.org/10.1016/j.jhepr.2019.100065DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7005564PMC
February 2020

A User's Guide to the Inverted Terminal Repeats of Adeno-Associated Virus.

Hum Gene Ther Methods 2019 12;30(6):206-213

Gene Therapy Research Unit, Children's Medical Research Institute and Sydney Children's Hospitals Network, University of Sydney, Westmead, Australia.

Ongoing development of recombinant vectors based on adeno-associated virus (rAAV) is providing an increasingly powerful and widely used toolkit for gene transfer and genome editing applications. While conceptually simple, the system harbors considerable complexity that presents many potential pitfalls for the inexperienced user. The short inverted terminal repeats (ITRs) can prove to be particularly problematic during vector engineering due to inherent instability necessitating diligent quality control measures during vector manufacture. This is especially important from a clinical standpoint when consistent purity and potency are paramount, and all components of the system are rigorously scrutinized by regulatory agencies. Despite the discovery over 30 years ago that the AAV ITRs are the only -acting elements of the virus required for vector production, there is a scarcity of reviews specifically focused on these complex elements. This review provides an overview of the ITR with the dual purpose of acting as a user's guide in the application of AAV vector technology and as a roadmap for ongoing vector development and optimization.
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http://dx.doi.org/10.1089/hgtb.2019.276DOI Listing
December 2019

Direct recognition of hepatocyte-expressed MHC class I alloantigens is required for tolerance induction.

JCI Insight 2018 08 9;3(15). Epub 2018 Aug 9.

Transplantation Immunobiology Group, University of Sydney Central Clinical School, Charles Perkins Centre, Faculty of Medicine and Health, Sydney, NSW, Australia.

Adeno-associated viral vector-mediated (AAV-mediated) expression of allogeneic major histocompatibility complex class I (MHC class I) in recipient liver induces donor-specific tolerance in mouse skin transplant models in which a class I allele (H-2Kb or H-2Kd) is mismatched between donor and recipient. Tolerance can be induced in mice primed by prior rejection of a donor-strain skin graft, as well as in naive recipients. Allogeneic MHC class I may be recognized by recipient T cells as an intact molecule (direct recognition) or may be processed and presented as an allogeneic peptide in the context of self-MHC (indirect recognition). The relative contributions of direct and indirect allorecognition to tolerance induction in this setting are unknown. Using hepatocyte-specific AAV vectors encoding WT allogeneic MHC class I molecules, or class I molecules containing a point mutation (D227K) that impedes direct recognition of intact allogeneic MHC class I by CD8+ T cells without hampering the presentation of processed peptides derived from allogeneic MHC class I, we show here that tolerance induction depends upon recognition of intact MHC class I. Indirect recognition alone yielded a modest prolongation of subsequent skin graft survival, attributable to the generation of CD4+ Tregs, but it was not sufficient to induce tolerance.
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http://dx.doi.org/10.1172/jci.insight.97500DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6129134PMC
August 2018

AAV-mediated gene delivery of the calreticulin anti-angiogenic domain inhibits ocular neovascularization.

Angiogenesis 2018 02 9;21(1):95-109. Epub 2018 Jan 9.

Department of Ophthalmology, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China.

Ocular neovascularization is a common pathological feature in diabetic retinopathy and neovascular age-related macular degeneration that can lead to severe vision loss. We evaluated the therapeutic efficacy of a novel endogenous inhibitor of angiogenesis, the calreticulin anti-angiogenic domain (CAD180), and its functional 112-residue fragment, CAD-like peptide 112 (CAD112), delivered using a self-complementary adeno-associated virus serotype 2 (scAAV2) in rodent models of oxygen-induced retinopathy and laser-induced choroidal neovascularization. The expression of CAD180 and CAD112 was elevated in human umbilical vein endothelial cells transduced with scAAV2-CAD180 or scAAV2-CAD112, respectively, and both inhibited angiogenic activity in vitro. Intravitreal gene delivery of scAAV2-CAD180 or scAAV2-CAD112 significantly inhibited ischemia-induced retinal neovascularization in rat eyes (CAD180: 52.7% reduction; CAD112: 49.2% reduction) compared to scAAV2-mCherry, as measured in retinal flatmounts stained with isolectin B4. Moreover, the retinal structure and function were unaffected by scAAV2-CAD180 or scAAV2-CAD112, as measured by optical coherence tomography and electroretinography. Moreover, subretinal delivery of scAAV2-CAD180 or scAAV2-CAD112 significantly attenuated laser-induced choroidal neovascularization in mouse eyes compared to scAAV2-mCherry, as measured by fundus fluorescein angiography (CAD180: 62.4% reduction; CAD112: 57.5% reduction) and choroidal flatmounts (CAD180: 40.21% reduction; CAD112: 43.03% reduction). Gene delivery using scAAV2-CAD180 or scAAV2-CAD112 has significant potential as a therapeutic option for the management of ocular neovascularization.
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http://dx.doi.org/10.1007/s10456-017-9591-4DOI Listing
February 2018

Identification of liver-specific enhancer-promoter activity in the 3' untranslated region of the wild-type AAV2 genome.

Nat Genet 2017 Aug 19;49(8):1267-1273. Epub 2017 Jun 19.

Gene Therapy Research Unit, Children's Medical Research Institute and Sydney Children's Hospitals Network, University of Sydney, Sydney, New South Wales, Australia.

Vectors based on adeno-associated virus type 2 (AAV2) are powerful tools for gene transfer and genome editing applications. The level of interest in this system has recently surged in response to reports of therapeutic efficacy in human clinical trials, most notably for those in patients with hemophilia B (ref. 3). Understandably, a recent report drawing an association between AAV2 integration events and human hepatocellular carcinoma (HCC) has generated controversy about the causal or incidental nature of this association and the implications for AAV vector safety. Here we describe and functionally characterize a previously unknown liver-specific enhancer-promoter element in the wild-type AAV2 genome that is found between the stop codon of the cap gene, which encodes proteins that form the capsid, and the right-hand inverted terminal repeat. This 124-nt sequence is within the 163-nt common insertion region of the AAV genome, which has been implicated in the dysregulation of known HCC driver genes and thus offers added insight into the possible link between AAV integration events and the multifactorial pathogenesis of HCC.
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http://dx.doi.org/10.1038/ng.3893DOI Listing
August 2017

Exploiting the unique regenerative capacity of the liver to underpin cell and gene therapy strategies for genetic and acquired liver disease.

Int J Biochem Cell Biol 2014 Nov 27;56:141-52. Epub 2014 Oct 27.

The Centre for Medical Research, Harry Perkins Institute of Medical Research, Crawley, WA 6009, Australia. Electronic address:

The number of genetic or acquired diseases of the liver treatable by organ transplantation is ever-increasing as transplantation techniques improve placing additional demands on an already limited organ supply. While cell and gene therapies are distinctly different modalities, they offer a synergistic alternative to organ transplant due to distinct architectural and physiological properties of the liver. The hepatic blood supply and fenestrated endothelial system affords relatively facile accessibility for cell and/or gene delivery. More importantly, however, the remarkable capacity of hepatocytes to proliferate and repopulate the liver creates opportunities for new treatments based on emerging technologies. This review will summarise current understanding of liver regeneration, describe clinical and experimental cell and gene therapeutic modalities and discuss critical challenges to translate these new technologies to wider clinical utility. This article is part of a Directed Issue entitled: "Regenerative Medicine: the challenge of translation".
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http://dx.doi.org/10.1016/j.biocel.2014.10.023DOI Listing
November 2014

The transcriptional and functional properties of mouse epiblast stem cells resemble the anterior primitive streak.

Cell Stem Cell 2014 Jan 17;14(1):107-20. Epub 2013 Oct 17.

Embryology Unit, Children's Medical Research Institute, Westmead NSW 2145, Australia; Sydney Medical School, University of Sydney, NSW 2006, Australia. Electronic address:

Mouse epiblast stem cells (EpiSCs) can be derived from a wide range of developmental stages. To characterize and compare EpiSCs with different origins, we derived a series of EpiSC lines from pregastrula stage to late-bud-stage mouse embryos. We found that the transcriptomes of these cells are hierarchically distinct from those of the embryonic stem cells, induced pluripotent stem cells (iPSCs), and epiblast/ectoderm. The EpiSCs display globally similar gene expression profiles irrespective of the original developmental stage of the source tissue. They are developmentally similar to the ectoderm of the late-gastrula-stage embryo and behave like anterior primitive streak cells when differentiated in vitro and in vivo. The EpiSC lines that we derived can also be categorized based on a correlation between gene expression signature and predisposition to differentiate into particular germ-layer derivatives. Our findings therefore highlight distinct identifying characteristics of EpiSCs and provide a foundation for further examination of EpiSC properties and potential.
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http://dx.doi.org/10.1016/j.stem.2013.09.014DOI Listing
January 2014

Adeno-associated virus-mediated rescue of neonatal lethality in argininosuccinate synthetase-deficient mice.

Mol Ther 2013 Oct 2;21(10):1823-31. Epub 2013 Jul 2.

Gene Therapy Research Unit, Children's Medical Research Institute and The Children's Hospital at Westmead, Sydney, Australia.

Viral vectors based on adeno-associated virus (AAV) are showing exciting promise in gene therapy trials targeting the adult liver. A major challenge in extending this promise to the pediatric liver is the loss of episomal vector genomes that accompanies hepatocellular proliferation during liver growth. Hence maintenance of sufficient transgene expression will be critical for success in infants and children. We therefore set out to explore the therapeutic efficacy and durability of liver-targeted gene transfer in the challenging context of a neonatal lethal urea cycle defect, using the argininosuccinate synthetase deficient mouse. Lethal neonatal hyperammonemia was prevented by prenatal and early postnatal vector delivery; however, hyperammonemia subsequently recurred limiting survival to no more than 33 days despite vector readministration. Antivector antibodies acquired in milk from vector-exposed dams were subsequently shown to be blocking vector readministration, and were avoided by crossfostering vector-treated pups to vector-naive dams. In the absence of passively acquired antivector antibodies, vector redelivery proved efficacious with mice surviving to adulthood without recurrence of significant hyperammonemia. These data demonstrate the potential of AAV vectors in the developing liver, showing that vector readministration can be used to counter growth-associated loss of transgene expression provided the challenge of antivector humoral immunity is addressed.
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http://dx.doi.org/10.1038/mt.2013.139DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3808136PMC
October 2013

Adeno-associated virus vectors: immunobiology and potential use for immune modulation.

Curr Gene Ther 2012 Aug;12(4):333-43

Gene Therapy Research Unit, Children's Medical Research Institute, Wentworthville, NSW, Sydney, Australia.

Recombinant viral vectors based on the human parvovirus, adeno-associated virus (AAV) show considerable promise for human therapeutic application. An important feature that sets this gene transfer system apart from other contemporary virus-based systems is relatively weak induction of innate and cognate immune responses, such that in defined contexts foreign antigens can be expressed long-term in immune competent hosts. This in turn has led to increasing interest in the possibility of exploiting AAV for immune system modulation, including both the induction and avoidance of antigen- specific responses, depending on the therapeutic need. This interest is fuelled by the recognition that the full potential of cell and gene based therapies cannot be realised without parallel developments in therapeutic immune system modulation that allow specific rather than generalised immunosuppression. This review outlines current understanding of AAV immunobiology and explores its potential as a tool for therapeutic manipulation of immune system responses.
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http://dx.doi.org/10.2174/156652312802083639DOI Listing
August 2012

Human induced pluripotent stem cells derived under feeder-free conditions display unique cell cycle and DNA replication gene profiles.

Stem Cells Dev 2012 Jan 1;21(2):206-16. Epub 2011 Jun 1.

Stem Cell Laboratory, School of Psychiatry, University of New South Wales, Sydney, Australia.

Use of animal feeder layers and serum containing media in the derivation and propagation of induced pluripotent stem cells (iPSCs) can hinder clinical translation, because of the presence of xeno-material/pathogens. A defined and standardized system would be ideal for generating a homogenous population of iPSCs, which closely resembles human embryonic stem cells (hESCs). This article presents a novel and extensive comparison between in-house produced iPSCs and hESCs under "feeder" and "feeder-free" conditions, using transcriptomic genome-wide microarray analysis. We generated a list of pluripotency-associated and bivalent domain-containing genes by meta-analysis to measure qualitatively the degree of reprogramming in feeder-free derived iPSCs, in which both profiles displayed similar levels of gene expression as in hESCs. Gene ontology analysis showed that feeder-free iPSCs have enriched terms belonging to DNA repair/replication and cell cycle, which are signature to pluripotent cells. Transcriptomic data combined with directed differentiation assays, indicated that variability among iPSC lines is minimized when using a feeder-free cultural system, which may serve as a platform for further developing regenerative medicine compliant human iPSCs.
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http://dx.doi.org/10.1089/scd.2010.0440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3258437PMC
January 2012

Liver-directed gene expression using recombinant AAV 2/8 vectors--a tolerogenic strategy for gene delivery?

Discov Med 2010 Jun;9(49):519-27

Transplantation Research Group, Bosch Institute, The University of Sydney, Sydney, NSW 2006, Australia.

Vectors based on recombinant adeno-associated virus (AAV) 2/8 hold considerable promise for use in human gene therapy. These vectors are safe, and have minimal immunostimulatory properties. Their combination with efficient, liver-specific promoters allows high-level transgene expression in the hepatocytes of small and large animals. In small animal models, this high level of liver expression results in tolerance to the transgene products. Tolerance to transgene products may also be achievable using these vectors for human gene therapy, but the HLA diversity (and thus variability in T cell recognition of transgene products) and high frequency of prior natural exposure to AAV in human populations impose additional challenges that must be overcome in order for this strategy to succeed.
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June 2010

Antigen fusion with C3d3 augments or inhibits humoral immunity to AAV genetic vaccines in a transgene-dependent manner.

Immunol Cell Biol 2010 Feb 24;88(2):228-32. Epub 2009 Nov 24.

Gene Therapy Research Unit, Children's Medical Research Institute and The Children's Hospital, Westmead, Australia.

Genetic fusion of tandem repeats of the complement molecule C3d has been shown to considerably enhance immune responses to genetic vaccines. We have investigated the applicability of this approach to augment humoral immune responses toward vaccines delivered by recombinant adeno-associated virus (AAV) vectors. C3d(3)-fusion was found to markedly decrease antibody responses to merozoite surface protein 4/5 from Plasmodium yoelii and contrasted with greater than 50-fold enhancement in responses when this strategy was similarly applied to another AAV-encoded model antigen, hen egg lysozyme. These data indicate that the efficacy of the C3d(3) strategy operates in an antigen-dependent manner. Additional studies also showed that homologous recombination events between the C3d tandem repeats occurred during vector packaging and transduction resulting in expression of C3d(1)-, C3d(2)-, C3d(3)- and C3d(4)-fused antigen. This is the first report to apply the C3d approach to augment responses against a recombinant viral vector system and the consequences of these findings are discussed.
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http://dx.doi.org/10.1038/icb.2009.92DOI Listing
February 2010

Gene therapy in transplantation.

Transplant Rev (Orlando) 2009 Jul 9;23(3):159-70. Epub 2009 May 9.

Collaborative Transplantation Research Group, Bosch Insitute, Royal Prince Alfred Hospital and University of Sydney, NSW 2006, Australia.

Gene therapy is an exciting and novel technology that offers the prospect of improving transplant outcomes beyond those achievable with current clinical protocols. This review explores both the candidate genes and ways in which they have been deployed to overcome both immune and non-immune barriers to transplantation success in experimental models. Finally, the major obstacles to implementing gene therapy in the clinic are considered.
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http://dx.doi.org/10.1016/j.trre.2009.04.001DOI Listing
July 2009

Gene delivery to the juvenile mouse liver using AAV2/8 vectors.

Mol Ther 2008 Jun 15;16(6):1081-8. Epub 2008 Apr 15.

Gene Therapy Research Unit, Children's Medical Research Institute and The Children's Hospital at Westmead, Wentworthville, Westmead, Australia.

Recombinant adeno-associated viral (rAAV) vectors have shown promise for use in liver-targeted gene delivery, but their effects have not been extensively investigated in the immature liver. Understanding the impact of liver growth on the efficacy of transduction is essential, because many monogenic liver diseases that are amenable to gene therapy will require treatment early in life. Here we show that rAAV2/8 transduces the neonatal mouse liver with high efficiency. With just one doubling in liver weight, however, there is a rapid reduction in vector genome numbers, irrespective of form, and the loss of episomal vector is almost complete by 2 weeks. Stable transgene expression is observed in a small percentage of hepatocytes, often in two- to eight-cell clusters, suggestive of genomic integration. Delivery at serially older ages was associated with progressively improved episome persistence and transgene expression. Vector re-administration was possible following initial neonatal administration, albeit at reduced efficacy because of an anticapsid humoral immune response. We also found that intraperitoneal (i.p.) delivery of rAAV2/8 was highly effective at all ages, and that promoter selection is the critical determinant of the intensity and pattern of transgene expression across the hepatic lobule. We conclude that successful use of rAAV to treat liver disease in early childhood will require optimally efficient vector constructs and probable re-administration.
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http://dx.doi.org/10.1038/mt.2008.72DOI Listing
June 2008

Robust anti-tumor immunity and memory in Rag-1-deficient mice following adoptive transfer of cytokine-primed splenocytes and tumor CD80 expression.

Cancer Immunol Immunother 2007 Dec 5;56(12):1955-65. Epub 2007 Jun 5.

Gene Therapy Research Unit, The Children's Hospital at Westmead and Children's Medical Research Institute, Westmead, NSW, Australia.

Successful immunotherapy of solid tumors has proven difficult to achieve. The aim of the current study was to further investigate the effects of peripheral CD80-mediated co-stimulation on the efficacy of polyclonal anti-tumor effector CTL in an adoptive transfer model. Splenocytes obtained from wild-type mice immunized with CD80-transduced EL4 tumor cells were expanded in vitro in the presence of either IL-12 or IL-15 and irradiated CD80-transduced EL4 tumor cells. Polyclonal CD8 T cells were the major subset in the effector population. Primed effector cells were adoptively transferred into immuno-deficient Rag-1-deficient mice which were then challenged with syngeneic vector-control or CD80-transduced EL4 tumor cells. Expression of CD80 enhanced the elimination of EL4 tumors and mouse survival. Both IL-12 and IL-15 cultured cells had enhanced cytotoxicity. Importantly, anti-tumor memory was maintained without tumor evasion following re-challenge with either CD80-transduced and vector-control EL4 cells. We also show, using antibody-mediated depletion, that endogenous NK cells present in Rag-1-deficient mice exert anti-EL4 tumor activity that is enhanced by CD80 expression. Collectively these data show that peripheral co-stimulation by tumor expression of CD80 results in enhanced anti-tumor efficacy of NK and polyclonal effector T cells, and suggest that TCR repertoire diversity helps protect against tumor escape and provides memory with resultant robust immunity to subsequent tumor challenge irrespective of CD80 status.
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http://dx.doi.org/10.1007/s00262-007-0339-7DOI Listing
December 2007

Limiting {gamma}c expression differentially affects signaling via the interleukin (IL)-7 and IL-15 receptors.

Blood 2007 Jul 15;110(1):91-8. Epub 2007 Mar 15.

Gene Therapy Research Unit, Children's Medical Research Institute and The Children's Hospital at Westmead, Australia.

X-linked severe combined immunodeficiency (SCID-X1) results from mutations in the IL2RG gene, which encodes the common gamma chain (gammac) of the receptors for interleukin (IL)-2, 4, 7, 9, 15, and 21. Affected infants typically lack T and natural killer (NK) cells as a consequence of loss of signaling via the IL-7 receptor (IL-7R) and the IL-15R, respectively. In some infants, however, autologous NK cells are observed despite failure of T-cell ontogeny. The mechanisms by which mutations in gammac differentially impact T- and NK-cell ontogeny remain incompletely understood. We used SCID-X1 patient-derived EBV-transformed B cells to test the hypothesis that the IL-15R-mediated signaling is preferentially retained as gammac expression becomes limiting. Signal transduction via the IL-15R was readily detected in control EBV-transformed B cells, and via the IL-7R when modified to express IL-7Ralpha. Under the same experimental conditions, patient-derived EBV-transformed B cells expressing trace amounts of gammac proved incapable of signal transduction via the IL-7R while retaining the capacity for signal transduction via the IL-15R. An equivalent result was obtained in ED-7R cells modified to express varying levels of gammac. Collectively, these results confirm that signal transduction via the IL-15R, and hence NK ontogeny, is preferentially retained relative to the IL-7R as gammac expression becomes limiting.
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http://dx.doi.org/10.1182/blood-2006-11-055442DOI Listing
July 2007

AAV vectors encoding malarial antigens stimulate antigen-specific immunity but do not protect from parasite infection.

Vaccine 2007 Jan 9;25(6):1014-22. Epub 2006 Oct 9.

Gene Therapy Research Unit, Children's Medical Research Institute and The Children's Hospital at Westmead, Westmead, Australia.

This study explores the utility of recombinant adeno-associated virus (rAAV) as a genetic vaccine delivery system using muscle as a target tissue. A single injection of rAAV encoding the malarial antigens MSP4 (Plasmodium falciparum) or MSP4/5 (Plasmodium yoelii) stimulated long-term antigen-specific antibody responses. Anti-MSP4/5 immunity stimulated by AAV was not protective against P. yoelii infection and efforts taken to augment antibody responses against MSP4/5, either by priming with plasmid DNA or AAV and boosting with rAAV were unsuccessful. Alternative strategies such as inclusion of genetic adjuvants into the AAV vector will be necessary to stimulate an adequate level of anti-malarial protective immunity in this model.
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http://dx.doi.org/10.1016/j.vaccine.2006.09.072DOI Listing
January 2007

CD4 expression on EL4 cells as an epiphenomenon of retroviral transduction and selection.

Immunol Cell Biol 2004 Apr;82(2):132-5

Gene Therapy Research Unit, Children's Medical Research Institute and The Children's Hospital at Westmead, Wentworthville, NSW, Australia.

The EL4 murine tumour cell line, isolated from a chemically induced lymphoma over 50 years ago, has been extensively exploited in immunological research. The conclusions drawn from many of these studies have been based on the presumption that EL4 cells maintain a stable phenotype during experimental manipulation. To the contrary, we have observed 100-fold greater expression of cell surface CD4 (CD4(high)) on a subpopulation of EL4 cells following retroviral transduction and G418 selection when compared with unmodified populations. Although the mechanism responsible for this effect remains to be elucidated, the unexpected expression of CD4, a molecule that functions as both a coreceptor with the T-cell receptor and ligand for the pro-inflammatory cytokine IL-16, has the potential to influence experimental outcomes. Upregulation of CD4 should be excluded when EL4 cells are utilized in experiments requiring a consistent immuno-phenotype.
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http://dx.doi.org/10.1046/j.0818-9641.2004.01228.xDOI Listing
April 2004

HeLa cells cocultured with peripheral blood lymphocytes acquire an immuno-inhibitory phenotype through up-regulation of indoleamine 2,3-dioxygenase activity.

Immunology 2002 Apr;105(4):478-87

Gene Therapy Research Unit of The Children's Medical Research Institute and The Children's Hospital at Westmead, Wentworthville NSW 2145, Westmead, Australia.

The mechanisms by which tumour cells escape recognition by the immune system or subvert antitumour effector responses remain poorly understood. In the course of investigating the potential of costimulatory signals in anticancer immunotherapy strategies, we have observed that HeLa cells (a human cervical carcinoma cell line) cocultured with peripheral blood lymphocytes (PBL) acquire the capacity to inhibit PBL proliferation in response to interleukin-2 (IL-2). This immuno-inhibitory phenotype was further shown to result from induction of the tryptophan-catabolizing enzyme, indoleamine 2,3-dioxygenase (IDO), by interferon-gamma (IFN-gamma) secreted from cocultured allo-reactive PBL. This enzyme has recently been shown to be a critically important modulator of immunological responses, most notably through the capacity to protect allogeneic concepti from alloreactive maternal lymphocytes. While the cytostatic consequences of IDO activity in tumour cells has received attention, the data presented in this report support the hypothesis that IDO activity may also act to impair antitumour immune responses.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1782674PMC
http://dx.doi.org/10.1046/j.1365-2567.2002.01390.xDOI Listing
April 2002
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