IL-7 surface-engineered lentiviral vectors promote survival and efficient gene transfer in resting primary T lymphocytes

Blood ◽  
2003 ◽  
Vol 101 (6) ◽  
pp. 2167-2174 ◽  
Author(s):  
Els Verhoeyen ◽  
Valerie Dardalhon ◽  
Odile Ducrey-Rundquist ◽  
Didier Trono ◽  
Naomi Taylor ◽  
...  
Keyword(s):  
Gene Therapy ◽  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Lentiviral Vectors ◽  
Target Cells ◽  
Interleukin 7 ◽  
Efficient Gene ◽  
Cognate Antigen ◽  
Therapy Target

Important gene therapy target cells such as resting human T cells are refractory to transduction with lentiviral vectors. Completion of reverse transcription, nuclear import, and subsequent integration of the lentiviral genome occur in these cells only if they have been activated. In T-cell–based gene therapy trials performed to date, cells have been activated via their cognate antigen receptor. To couple activation with gene transfer, we previously generated lentiviral vectors displaying an anti-CD3 scFv fragment that allowed up to 48% transduction of freshly isolated T cells. However, transduction of highly purified resting T cells with these anti-CD3–displaying lentiviral vectors was inefficient and shifted the T cells from the naive to the memory phenotype. Here, we describe interleukin-7 (IL-7)–displaying HIV-1–derived vectors. Like recombinant IL-7, these modified particles could promote the survival of primary T cells placed in culture without inducing a naive-to-memory phenotypic switch. Furthermore, a single exposure to the IL-7–displaying vectors resulted in efficient gene transfer in both resting memory adult T cells and naive cord blood T cells. With adult naive T cells, preactivation with recombinant IL-7 was necessary for efficient gene transfer. Altogether, these results suggest that IL-7–displaying vectors could constitute interesting tools for T-cell–targeted gene therapy.

Stable transduction of quiescent T cells without induction of cycle progression by a novel lentiviral vector pseudotyped with measles virus glycoproteins

Blood ◽  
2008 ◽  
Vol 112 (13) ◽  
pp. 4843-4852 ◽  
Author(s):  
Cecilia Frecha ◽  
Caroline Costa ◽  
Didier Nègre ◽  
Emmanuel Gauthier ◽  
Stephen J. Russell ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Gene Therapy ◽  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Measles Virus ◽  
Lentiviral Vectors ◽  
Cell Cycle Entry ◽  
Efficient Gene ◽  
Quiescent T Cells

AbstractA major limitation of current lentiviral vectors (LVs) is their inability to govern efficient gene transfer into quiescent cells such as primary T cells, which hampers their application for gene therapy. Here we generated high-titer LVs incorporating Edmonston measles virus (MV) glycoproteins H and F on their surface. They allowed efficient transduction through the MV receptors, SLAM and CD46, both present on blood T cells. Indeed, these H/F-displaying vectors outperformed by far VSV-G-LVs for the transduction of IL-7–prestimulated T cells. More importantly, a single exposure to these H/F-LVs allowed efficient gene transfer in quiescent T cells, which are not permissive for VSV-G-LVs that need cell-cycle entry into the G1b phase for efficient transduction. High-level transduction of resting memory (50%) and naive (11%) T cells with H/F-LVs, which seemed to occur mainly through SLAM, was not at cost of cell-cycle entry or of target T-cell activation. Finally, the naive or memory phenotypes of transduced resting T cells were maintained and no changes in cytokine profiles were detected, suggesting that T-cell populations were not skewed. Thus, H/F-LV transduction of resting T cells overcomes the limitation of current lentiviral vectors and may improve the efficacy of T cell–based gene therapy.

Clonal Analyses of Retroviral Vector Integrations in ADA-SCID Patients Treated with Stem Cell Gene Therapy.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3249-3249
Author(s):  
Barbara Cassani ◽  
Grazia Andolfi ◽  
Massimiliano Mirolo ◽  
Luca Biasco ◽  
Alessandra Recchia ◽  
...  
Keyword(s):  
Gene Therapy ◽  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Human Genome ◽  
Ex Vivo ◽  
Cd34 Cells

Abstract Gene transfer into hematopoietic stem/progenitor cells (HSC) by gammaretroviral vectors is an effective treatment for patients affected by severe combined immunodeficiency (SCID) due to adenosine deaminase (ADA)-deficiency. Recent studied have indicated that gammaretroviral vectors integrate in a non-random fashion in their host genome, but there is still limited information on the distribution of retroviral insertion sites (RIS) in human long-term reconstituting HSC following therapeutic gene transfer. We performed a genome-wide analysis of RIS in transduced bone marrow-derived CD34+ cells before transplantation (in vitro) and in hematopoietic cell subsets (ex vivo) from five ADA-SCID patients treated with gene therapy combined to low-dose busulfan. Vector-genome junctions were cloned by inverse or linker-mediated PCR, sequenced, mapped onto the human genome, and compared to a library of randomly cloned human genome fragments or to the expected distribution for the NCBI annotation. Both in vitro (n=212) and ex vivo (n=496) RIS showed a non-random distribution, with strong preference for a 5-kb window around transcription start sites (23.6% and 28.8%, respectively) and for gene-dense regions. Integrations occurring inside the transcribed portion of a RefSeq genes were more represented in vitro than ex vivo (50.9 vs 41.3%), while RIS <30kb upstream from the start site were more frequent in the ex vivo sample (25.6% vs 19.4%). Among recurrently hit loci (n=50), LMO2 was the most represented, with one integration cloned from pre-infusion CD34+ cells and five from post-gene therapy samples (2 in granulocytes, 3 in T cells). Clone-specific Q-PCR showed no in vivo expansion of LMO2-carrying clones while LMO2 gene overexpression at the bulk level was excluded by RT-PCR. Gene expression profiling revealed a preference for integration into genes transcriptionally active in CD34+ cells at the time of transduction as well as genes expressed in T cells. Functional clustering analysis of genes hit by retroviral vectors in pre- and post-transplant cells showed no in vivo skewing towards genes controlling self-renewal or survival of HSC (i.e. cell cycle, transcription, signal transduction). Clonal analysis of long-term repopulating cells (>=6 months) revealed a high number of distinct RIS (range 42–121) in the T-cell compartment, in agreement with the complexity of the T-cell repertoire, while fewer RIS were retrieved from granulocytes. The presence of shared integrants among multiple lineages confirmed that the gene transfer protocol was adequate to allow stable engraftment of multipotent HSC. Taken together, our data show that transplantation of ADA-transduced HSC does not result in skewing or expansion of malignant clones in vivo, despite the occurrence of insertions near potentially oncogenic genomic sites. These results, combined to the relatively long-term follow-up of patients, indicate that retroviral-mediated gene transfer for ADA-SCID has a favorable safety profile.

AAV-2 Capsid-Specific CD8+ T Cells Limit the Duration of Gene Therapy in Humans and Cross-React with AAV-8 Capsid.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 455-455 ◽  
Author(s):  
Federico Mingozzi ◽  
Marcela V. Maus ◽  
Denise E. Sabatino ◽  
Daniel J. Hui ◽  
John E.J. Rasko ◽  
...  
Keyword(s):  
Gene Therapy ◽  
T Cells ◽  
T Cell ◽  
Cell Population ◽  
Cd8 T Cells ◽  
Peripheral Blood ◽  
Transgene Expression ◽  
Cd8 T Cell ◽  
Target Cells

Abstract Efforts to establish an adeno-associated viral (AAV) vector-mediated gene therapy for the treatment of hemophilia B have been hindered by an immune response to the viral capsid antigen. Preclinical studies in small and large animal models of the disease showed long-term factor IX (F.IX) transgene expression and correction of the phenotype. However, in a recent phase I/II clinical trial in humans (Manno et al., Nat. Med. 2006), after hepatic gene transfer with an AAV-2 vector expressing human F.IX transgene, expression lasted for only a few weeks, declining to baseline concurrently with a peak in liver enzymes. We hypothesized that T cells directed towards AAV capsid antigens displayed by transduced hepatocytes were activated and these mediated destruction of the transduced hepatocytes, thereby causing loss of transgene expression and a transient transaminitis. Peripheral blood mononuclear cells isolated from AAV-infused subjects were stained with an AAV capsid-specific MHC class I pentamer either directly or after in vitro expansion. Two weeks after vector infusion 0.14% of circulating CD8+ T cells were capsid-specific on direct staining, and five weeks after infusion the capsid-specific population had expanded to 0.5% of the circulating CD8+ T cells, indicating proliferation of this T cell subset. By 20 weeks after vector infusion, the capsid-specific CD8+ T cell population had contracted to the level seen at 2 weeks. The expansion and contraction of this capsid-specific CD8+ T cell population paralleled the rise and fall of serum transaminases in the subject observed. Subsequent ex vivo studies of PBMC showed the presence of a readily expandable pool of capsid-specific CD8+ T cells up to 2.5 years post vector-infusion. Similarly, we were able to expand AAV-specific CD8+ T cells from peripheral blood of normal donors, suggesting the existence of a T cell memory pool. Expanded CD8+ T cells were functional as evidenced by specific lysis of HLA-matched target cells and by IFN-γsecretion in response to AAV epitopes. It has been argued that potentially harmful immune responses could be avoided by switching AAV serotypes, however, capsid protein sequences are highly conserved among different serotypes, as are some immunodominant epitopes that we identified. Indeed, we demonstrated that capsid-specific CD8+ T cells from AAV-infused hemophilic subjects functionally cross-react with AAV-8. Moreover, cells expanded from normal donors with AAV-2 vector capsids proliferated upon culture with AAV-8 capsids, demonstrating that both vectors could be processed appropriately in vitro to present the epitopic peptide to capsid-specific T cells. This suggests that AAV-2-specific memory CD8+ T cells normally present in humans likely would expand upon exposure to AAV-8 capsid epitopes. We conclude that the use of immunomodulatory therapy may be a better approach to achieving durable transgene expression in the setting of AAV-mediated gene therapy.

scholarly journals Foamy Virus Based Vectors for CAR-T Cell Development

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4646-4646
Author(s):  
Emmanouil Simantirakis ◽  
Vassilis Atsaves ◽  
Ioannis Tsironis ◽  
Margarita Gkyzi ◽  
Kostas Konstantopoulos ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Peripheral Blood ◽  
Transduction Efficiency ◽  
Target Cells ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Ifn Γ

Introduction A novel approach that can cover the therapeutic gap in NHL treatment are the autologous T cells, expressing Chimeric Antigen Receptors (CAR-T cells) against tumor markers. Such clinical-grade products based on Lenti (LV) or Retro- vectors have hit the market. An alternative vector system for CAR gene transfer in T-cells are Foamy Viruses (FV). To evaluate the potential of FV vectors in CAR-T cell development, we synthesized an antiCD19 scFv cDNA and cloned it in both an FV and an LV backbone; both vectors were tested in paired experiments Material and Methods The anti-CD19 CAR was under the control of the EF1a promoter; EGFP expression was under the control of an IRES2 element. The anti-CD19 CAR sequence was deduced from published data. FV vectors were made with a 4-plasmid vector system in 293T cells. 2nd generation LV vectors were purchased from Addgene. Cord blood (CB), healthy donor peripheral blood (PB) and CLL patients' PB was used as a source for CD3+ cells using immunomagnetic enrichment. Informed consent has been obtained in all cases of human sample use. T cells were activated by antiCD3/CD28 beads and transduced with antiCD19 LV or FV vectors. Transduction efficiency was assayed by flow cytometry (FCM) using a PE-conjugated anti-mouse Fab antibody. FV and LV CAR-T cells were expanded with Rapid Expansion Protocol (REP) and their cytotoxicity assays was evaluated against the CD19+ cell lines Raji and Daudi. The CLL patient derived CAR-Ts were evaluated against autologous B cells. Cytotoxicity was evaluated with an FCM protocol using CFSE-stained target cells vs unstained effector CARTs in different ratios. At the end of the incubation cells were stained with 7AAD to discriminate against live/dead cells. CAR-T cell activation was also assayed by INF-γ ELISA, following cocultures with target cells at a ratio of 1:1 for 24h. Results Vector titers: LV vector titers were between 3-5x10^5 TU/ml for both LV vectors (with or without EGFP cassette). FV vector titers were between 2-4x10^5 TU/ml regardless of the presence of the EGFP cassette. Tx efficiency: FV can mediate efficient gene transfer on T cells in the presence of heparin at an effective dose of 20-40 U/ml using a spinoculation technique. Transduction efficiency ranged from 40-65% at MOI=3-5, and was comparable to the transduction efficiency of LV vectors at a much higher MOI (10 to 30). Cytotoxicity data on lines: Following REP, the cell population consisted mostly (close to 96% purity) of CAR-T cells regardless of the vector used or of the T cell source. Effector cells were cocultured with the CD19+ cell lines, Daudi and Raji at varying ratios. With cord blood derived FV-CAR-T cells, at 4h post coculture we observed a 39.4% cell lysis at a ratio of 10:1 effector to target (n=1). Similar results were obtained for LV vectors. Peripheral blood derived CAR-T cells at THE same ratio (10:1), demonstrated 83.9% and 93.1% cell lysis for FV-CART and LV-CART cells respectively (n=2). Cytotoxicity data on CLL cells: T-cells from peripheral blood of CLL patients were used to generate LV- and FV-CAR-T cells. At the ratio of 10:1, we observed 73.1% and 69,8% cytotoxicity for FV-CAR-Ts and 70.1% and 70.7% with LV-CAR-Ts, in 2 independent paired experiments. IFN as activation marker: In two paired activation experiments, CB-derived FV-CAR-T cells secrete 560 and 437pg/ml of IFN-γ; similarly, LV-CAR-Ts secrete 534 and 554pg/ml IFN-γ. Untransduced control cells, produced 68pg/ml and 12pg/ml for FV-CAR-T and LV-CAR-T experimental arm respectively. Conclusion In the current work, we developed and tested FV vectors for anti- CD19 CAR-T cell production. We proved that FV viral vectors are capable of mediating efficient gene transfer to human T cells. We developed a method to efficiently transfer FV vectors into T-cells, using a clinically relevant protocol with heparin. The FV-derived CAR T cells demonstrate the same cytotoxic properties in vitro as their LV-derived counterpart and the same activation levels in the presence of CD19 expressing target cells as measured by IFN-γ secretion. FV CARTs derived from PB of CLL patients were capable of mediating comparable cytotoxicity levels as their LV-derived counterparts. Overall, we provide a proof of concept that FVs could be a safe and efficient alternative to LV derived vectors for CAR-T cells. Disclosures No relevant conflicts of interest to declare.

Re-Engineering γ δ T Cells by α β T Cell Receptor Gene Transfer Creates Potent Effector Cells with Anti-Leukemic Reactivity.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 1288-1288
Author(s):  
Lars T. van der Veken ◽  
Renate S. Hagedoorn ◽  
Marleen M. van Loenen ◽  
Roel Willemze ◽  
J.H. Frederik Falkenburg ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Peripheral Blood ◽  
Cytokine Production ◽  
Target Cells ◽  
Facs Analysis ◽  
Effector Cells ◽  
Tetramer Binding ◽  
Potent Effector

Abstract Retroviral transfer of T cell receptors (TCRs) to peripheral blood derived T cells generates large numbers of T cells with the same antigen specificity, which can potentially be used for adoptive immunotherapy. One drawback of this procedure is the formation of mixed α β TCR dimers with unknown specificities due to pairing of endogenous and introduced TCR chains. To completely prevent the formation of mixed TCR dimers by TCR gene transfer to α β T cells we investigated whether γ δ T cells can serve as alternative host T cells for α β TCR transfer, since the γ δ TCR is not capable of forming dimers with the α β TCR. Peripheral blood derived γ δT cells were isolated by immunomagnetic bead isolation and subsequent FACS sorting, resulting in &gt;99% pure populations of γ δT cells. The isolated γ δT cells were retrovirally transduced with three different TCRs specific for the hematopoietic minor histocompatibility antigen (mHag) HA-2 in the context of HLA-A2, for CMV-pp65 in the context of HLA-B7, or for the HLA class II restricted mHag DBY. The TCR-transduced γ δT cells expressed both the introduced TCRs and the endogenous γ δTCR at their cell surface as determined by FACS analysis. When γ δT cells transduced with the HLA class I restricted HA-2-TCR or CMV-TCR were stained with tetramers, only the CMV-TCR expressing γ δT cells but not the HA-2-TCR expressing γ δT cells were capable of strong antigen specific tetramer binding. In contrast, functional analysis indicated that all TCR-transduced γ δT cells specifically recognized peptide pulsed target cells leading to target cell lysis and IFNγ and IL-4 production, indicating that while the avidity of the HA-2-TCR engineered γ δT cells was insufficient for strong antigen specific tetramer binding, the avidity was high enough for the specific recognition of peptide pulsed target cells. However, the functional reactivity of the TCR-transduced γ δT cells against target cells presenting endogenously processed antigens was low. FACS analysis indicated that most γ δT cells lacked the expression of the coreceptors CD4 and CD8. Therefore, we investigated whether introduction of the relevant coreceptor could enhance the functionality of the redirected γ δT cells. Co-transfer of the CD8α β coreceptor to the HA-2-TCR and CMV-TCR transferred γ δT cells turned them into effective, antigen specific tetramer binders. Furthermore, expression of CD8α β by the HA-2-TCR and CMV-TCR transduced γ δT cells and CD4 by the DBY-TCR transduced γ δT cells generated powerful effector cells exerting high levels of antigen specific lysis of both peptide pulsed target cells and target cells presenting endogenously processed antigen. In addition, coreceptor expressing TCR-engineered γ δT cells produced high amounts of IFNγ and IL-4 when stimulated with peptide pulsed target cells or endogenously processed antigen. To investigate the anti-leukemic reactivity of TCR-transferred γ δT cells, we determined the antigen specific cytotoxicity and cytokine production against primary CML and AML cells by γ δT cells equipped with the HA-2-TCR and CD8α β . We observed both antigen specific cytolytic activity and cytokine production against both CML and AML cells expressing the hematopoiesis specific mHag HA-2, while HLA-A2+ leukemic cells lacking expression of the HA-2 mHag were not recognized. These data demonstrate that transfer of α β TCRs to γ δT cells generated potent effector cells for immunotherapy of leukemia, without the expression of potentially hazardous mixed TCR dimers.

T Cell Receptor Gene Transfer to Virus-Specific T Cells for Cellular Anti-Tumor Immunotherapy.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2594-2594
Author(s):  
Marieke Griffioen ◽  
H.M. Esther van Egmond ◽  
Menno A.W.G. van der Hoorn ◽  
Renate S. Hagedoorn ◽  
Michel Kester ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Tumor Immunotherapy ◽  
Surface Expression ◽  
Target Cells ◽  
Clinical Grade ◽  
Specific Lysis ◽  
High Frequencies ◽  
Dual Specificity

Abstract Patients with relapsed hematological malignancies after allogeneic stem cell transplantation (alloSCT) can be successfully treated by donor lymphocyte infusions (DLI). Since DLI consists of a variety of T cells with different specificities, the benificial anti-leukemic effect of DLI is often accompanied by Graft-versus-Host Disease (GvHD). Genetic modification of T cells to express T cell receptors (TCR) with defined anti-tumor specificity would be an attractive strategy to specifically eradicate the malignant cells without induction of GvHD. We previously demonstrated that transfer of the minor histocompatibility antigen HA-2 specific TCR to CMV specific T cells led to the generation of T cells with dual specificity for CMV as well as HA-2. CMV and EBV specific T cells are ideal target cells for TCR gene transfer, since the majority of human individuals have high frequencies of these T cells due to latent persistence of CMV and EBV. In addition, based on their virus specificity, these T cells do not induce GvHD in an alloSCT setting, and we hypothesize that due to frequent encounter with viral antigens, TCR transferred virus specific T cells will survive for a prolonged period of time in vivo. The aim of this study is to develop a clinical grade method for the generation of TCR transduced virus specific T cells for cellular immunotherapy. CMV and EBV specific T cells were isolated from healthy individuals using pentamers in combination with clinical grade available anti-biotin magnetic beads. Isolation by pentamer-coated beads induced stimulation, expansion and efficient transduction of virus specific T cells, leading to the generation of cell lines with high frequencies of virus specific (&gt;80%) and transduced (20–40%) T cells. T cells were transduced with multi-cistronic retroviral vectors encoding the α and β chains of the HA-2 TCR linked by an IRES or 2A-like sequence. No differences in transduction efficiency and TCR surface expression were observed between the IRES and 2A-like vectors. The transduced virus specific T cells were shown to exhibit dual specificity and tetramer staining of the introduced TCR correlated with specific lysis of target cells endogenously-expressing HA-2. Furthermore, variation in surface expression of the introduced TCR was observed between T cells with different virus specificities. T cells directed against the HLA-A1 epitope of CMV-pp50, for example, efficiently expressed the HA-2 TCR, whereas T cells specific for the HLA-B8 epitope of EBV-EBNA-3A did not express the introduced TCR. Functional analyses demonstrated that TCR-transduced pp50 specific T cells were dual specific, recognizing HA-2 as well as pp50 positive target cells, whereas TCR-engineered EBNA-3A specific T cells were primarily EBNA-3A specific. The efficiency of surface expression of the transferred TCR was shown to be determined by intrinsic properties of the TCRs, illustrating that for TCR gene transfer purposes TCRs need to be selected that exhibit high competition potential, whereas recipient T cells need to express endogenous TCRs with low competition potential. For clinical application, TCRs will be transferred to virus specific T cells selected for their capacity to efficiently express the introduced TCR without loss of virus specificity. The safety, clinical and immunological efficacy of TCR gene transfer to virus specific T cells as cellular anti-tumor immunotherapy after alloSCT will be investigated in a clinical phase I/II study.

Efficient gene transfer into human primary blood lymphocytes by surface-engineered lentiviral vectors that display a T cell–activating polypeptide

Blood ◽  
2002 ◽  
Vol 99 (7) ◽  
pp. 2342-2350 ◽  
Author(s):  
Marielle Maurice ◽  
Els Verhoeyen ◽  
Patrick Salmon ◽  
Didier Trono ◽  
Stephen J. Russell ◽  
...  
Keyword(s):  
T Cell ◽  
Gene Transfer ◽  
Gene Delivery ◽  
Genetic Material ◽  
Lentiviral Vectors ◽  
Target Cells ◽  
Single Chain ◽  
Single Chain Antibody ◽  
Blood Lymphocytes ◽  
Hiv 1

In contrast to oncoretroviruses, lentiviruses such as human immunodeficiency virus 1 (HIV-1) are able to integrate their genetic material into the genome of nonproliferating cells that are metabolically active. Likewise, vectors derived from HIV-1 can transduce many types of nonproliferating cells, with the exception of some particular quiescent cell types such as resting T cells. Completion of reverse transcription, nuclear import, and subsequent integration of the lentivirus genome do not occur in these cells unless they are activated via the T-cell receptor (TCR) or by cytokines or both. However, to preserve the functional properties of these important gene therapy target cells, only minimal activation with cytokines or TCR-specific antibodies should be performed during gene transfer. Here we report the characterization of HIV-1–derived lentiviral vectors whose virion surface was genetically engineered to display a T cell-activating single-chain antibody polypeptide derived from the anti-CD3 OKT3 monoclonal antibody. Interaction of OKT3 IgGs with the TCR can activate resting peripheral blood lymphocytes (PBLs) by promoting the transition from G0 to G1 phases of the cell cycle. Compared to unmodified HIV-1–based vectors, OKT3-displaying lentiviral vectors strongly increased gene delivery in freshly isolated PBLs by up to 100-fold. Up to 48% transduction could be obtained without addition of PBL activation stimuli during infection. Taken together, these results show that surface-engineered lentiviral vectors significantly improve transduction of primary lymphocytes by activating the target cells. Moreover these results provide a proof of concept for an approach that may have utility in various gene transfer applications, including in vivo gene delivery.

scholarly journals Effect of CpG Depletion of Vector Genome on CD8+ T Cell Responses in AAV Gene Therapy

2021 ◽  
Vol 12 ◽  
Author(s):  
Thais B. Bertolini ◽  
Jamie L. Shirley ◽  
Irene Zolotukhin ◽  
Xin Li ◽  
Tsuneyasu Kaisho ◽  
...  
Keyword(s):  
Gene Therapy ◽  
Clinical Trials ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Immune Responses ◽  
Cell Responses ◽  
Cpg Motifs ◽  
Vector Genome

Adeno associated viral (AAV) vectors have emerged as a preferred platform for in vivo gene replacement therapy and represent one of the most promising strategies to treat monogenetic disorders such as hemophilia. However, immune responses to gene transfer have hampered human gene therapy in clinical trials. Over the past decade, it has become clear that innate immune recognition provides signals for the induction of antigen-specific responses against vector or transgene product. In particular, TLR9 recognition of the vector’s DNA genome in plasmacytoid dendritic cells (pDCs) has been identified as a key factor. Data from clinical trials and pre-clinical studies implement CpG motifs in the vector genome as drivers of immune responses, especially of CD8+ T cell activation. Here, we demonstrate that cross-priming of AAV capsid-specific CD8+ T cells depends on XCR1+ dendritic cells (which are likely the main cross-presenting cell that cooperates with pDCs to activate CD8+ T cells) and can be minimized by the elimination of CpG motifs in the vector genome. Further, a CpG-depleted vector expressing human coagulation factor IX showed markedly reduced (albeit not entirely eliminated) CD8+ T cell infiltration upon intramuscular gene transfer in hemophilia B mice when compared to conventional CpG+ vector (comprised of native sequences), resulting in better preservation of transduced muscle fibers. Therefore, this deimmunization strategy is helpful in reducing the potential for CD8+ T cell responses to capsid or transgene product. However, CpG depletion had minimal effects on antibody responses against capsid or transgene product, which appear to be largely independent of CpG motifs.

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