Chemokine receptor 5 knockout strategies - PubMed (original) (raw)

Review

Chemokine receptor 5 knockout strategies

Paula Cannon et al. Curr Opin HIV AIDS. 2011 Jan.

Abstract

Purpose of review: Individuals homozygous for a deletion in the chemokine receptor 5 (CCR5) gene (CCR5Δ32) are almost completely resistant to HIV-1 infection. A recent report that transplantation of hematopoietic stem or progenitor cells (HSCs) from a CCR5Δ32 homozygous donor effectively cured an HIV patient has increased interest in the development of strategies that could be used to recreate this phenotype using a patient's own cells. This review will focus on recent developments to disrupt CCR5 expression in both autologous T cells and HSCs.

Recent findings: CCR5 expression in HIV-1 target cells can be suppressed by RNA-based gene suppression technologies such as RNA interference, or completely eliminated by zinc finger nuclease (ZFN)-mediated gene disruption. ZFNs bind specifically to a DNA sequence and generate a double-stranded DNA break, whose subsequent repair by the cell's error-prone nonhomologous end-joining pathway can lead to permanent disruption of the gene's open reading frame. Recent developments in humanized mouse models have facilitated preclinical studies that have demonstrated the ability of CCR5-targeted ZFNs to suppress HIV-1 in vivo, when used to modify human T cells or HSCs. The same CCR5 ZFNs are now being evaluated in a phase I clinical trial of ex vivo expanded autologous T cells.

Summary: CCR5 gene knockout in T cells or HSCs by ZFNs effectively suppresses the replication of CCR5-tropic strains of HIV-1 in animal models. ZFNs are currently being evaluated in a phase I clinical trials using ex vivo expanded T cells and HSCs targeted therapies are under development.

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Figures

Figure 1

Figure 1. Gene knockout by zinc finger nucleases

Schematic showing recognition of a specific CCR5 sequence by two ZFNs that subsequently cleave the DNA. Repair by the NHEJ pathway leads to a variety of insertions or deletions at the break site, including the frequent (25%) 5bp duplication [**22,**23] that is depicted and which introduces two premature stop codons in the ORF.

Figure 2

Figure 2. Clinical applications of CCR5 ZFNs

CCR5 knockout in autologous T cells or HSC can be achieved by transduction with an Ad5/35 vector (SB-728) expressing left and right ZFNs, linked by a self-cleaving protease 2A sequence. In an ongoing phase I clinical trial, the CCR5 modified T cells are expanded ex vivo using antibodies to CD3 and CD28 for approximately 10 days and adoptively transferred to the patient (protocol NCT00842634). Also depicted is a possible clinical trial in AIDS lymphoma patients using autologous CD34+ HSC, purified from peripheral blood following G-CSF mobilization. Chemotherapy is given as part of the lymphoma treatment and also assists the engraftment of the modified HSC.

References

    1. Wu L, Gerard NP, Wyatt R, et al. CD4-induced interaction of primary HIV-1 gp120 glycoproteins with the chemokine receptor CCR-5. Nature. 1996;6605:179–183. -PubMed
    1. Samson M, Libert F, Doranz BJ, et al. Resistance to HIV-1 infection in Caucasian individuals bearing mutant alleles of the CCR-5 chemokine receptor gene. Nature. 1996;6593:722–725. -PubMed
    1. Chalmet K, Van Wanzeele F, Demecheleer E, et al. Impact of Delta 32-CCR5 heterozygosity on HIV-1 genetic evolution and variability--a study of 4 individuals infected with closely related HIV-1 strains. Virology. 2008;379:213–222. -PubMed
    1. Hardy WD, Gulick RM, Mayer H, et al. Two-Year safety and virologic efficacy of Maraviroc in treatment-experienced patients with CCR5-tropic HIV-1 infection: 96-week combined analysis of MOTIVATE 1 and 2. J Acquir Immune Defic Syndr. 2010 Aug 11; [Epub ahead of print]. Results from 2 year follow up of over 1,000 treatment-experienced patients enrolled in 2 prospective studies of Maraviroc safety and efficacy. Durable anti-HIV responses were observed. -PMC -PubMed
    1. Westby M, van der Ryst E. CCR5 antagonists: host-targeted antiviral agents for the treatment of HIV infection, 4 years on. Antivir Chem Chemother. 2010;20:179–192. 6. -PubMed

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