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The impact of GPIb? on platelet-targeted FVIII gene therapy in hemophilia A mice with pre-existing anti-FVIII immunity.

ABSTRACT: Essentials Platelet-specific FVIII gene therapy is effective in hemophilia A mice even with inhibitors. The impact of platelet adherence via VWF/GPIb? binding on platelet gene therapy was investigated. GPIb? does not significantly affect platelet gene therapy of hemophilia A with inhibitors. Platelet gene therapy induces immune tolerance in hemophilia A mice with pre-existing immunity. SUMMARY: Background We have previously demonstrated that von Willebrand factor (VWF) is essential in platelet-specific FVIII (2bF8) gene therapy of hemophilia A (HA) with inhibitory antibodies (inhibitors). At the site of injury, platelet adherence is initiated by VWF binding to the platelet GPIb complex. Objective To investigate the impact of GPIb? on platelet gene therapy of HA with inhibitors. Methods Platelet-FVIII expression was introduced by 2bF8 lentivirus (2bF8LV) transduction of hematopoietic stem cells (HSCs) from GPIb?null (Ibnull ) mice or rhF8-primed FVIIInull (F8null ) mice followed by transplantation into lethally irradiated rhF8-primed F8null recipients. Animals were analyzed by flow cytometry, FVIII assays and the tail bleeding test. Results After transplantation, 99% of platelets were derived from donors. The macrothrombocytopenia phenotype was maintained in F8null mice that received 2bF8LV-transduced Ibnull HSCs (2bF8-Ibnull /F8null ). The platelet-FVIII expression level in 2bF8-Ibnull /F8null recipients was similar to that obtained from F8null mice that received 2bF8LV-transduced F8null HSCs (2bF8-F8null /F8null ). The tail bleeding test showed that the remaining hemoglobin level in the 2bF8-Ibnull /F8null group was significantly higher than in the F8null control group, but there was no significant difference between the 2bF8-Ibnull /F8null and 2bF8-F8null /F8null groups. The half-life of inhibitor disappearance time was comparable between the 2bF8-Ibnull /F8null and 2bF8-F8null /F8null groups. The rhF8 re-challenge did not elicit a memory immune response once inhibitor titers dropped to undetectable levels after 2bF8 gene therapy. Conclusion GPIb? does not significantly impact platelet gene therapy of HA with inhibitors. 2bF8 gene therapy restores hemostasis and promotes immune tolerance in HA mice with pre-existing immunity.

SUBMITTER: Chen J

PROVIDER: S-EPMC6397061 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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The impact of GPIbα on platelet-targeted FVIII gene therapy in hemophilia A mice with pre-existing anti-FVIII immunity.

Chen Juan J Schroeder Jocelyn A JA Luo Xiaofeng X Montgomery Robert R RR Shi Qizhen Q

Journal of thrombosis and haemostasis : JTH 20190203 3

Essentials Platelet-specific FVIII gene therapy is effective in hemophilia A mice even with inhibitors. The impact of platelet adherence via VWF/GPIbα binding on platelet gene therapy was investigated. GPIbα does not significantly affect platelet gene therapy of hemophilia A with inhibitors. Platelet gene therapy induces immune tolerance in hemophilia A mice with pre-existing immunity. SUMMARY: Background We have previously demonstrated that von Willebrand factor (VWF) is essential in platelet-s ...[more]

PMID: 30609275

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Project description:Adeno-associated virus (AAV)-mediated gene therapy may provide durable protection from bleeding events and reduce treatment burden for people with hemophilia A (HA). However, pre-existing immunity against AAV may limit transduction efficiency and hence treatment success. Global data on the prevalence of AAV serotypes are limited. In this global, prospective, noninterventional study, we determined the prevalence of pre-existing immunity against AAV2, AAV5, AAV6, AAV8, and AAVrh10 among people ≥12 years of age with HA and residual FVIII levels ≤2 IU/dL. Antibodies against each serotype were detected using validated, electrochemiluminescent-based enzyme-linked immunosorbent assays. To evaluate changes in antibody titers over time, 20% of participants were retested at 3 and 6 months. In total, 546 participants with HA were enrolled at 19 sites in 9 countries. Mean (standard deviation) age at enrollment was 36.0 (14.87) years, including 12.5% younger than 18 years, and 20.0% 50 years of age and older. On day 1, global seroprevalence was 58.5% for AAV2, 34.8% for AAV5, 48.7% for AAV6, 45.6% for AAV8, and 46.0% for AAVrh10. Considerable geographic variability was observed in the prevalence of pre-existing antibodies against each serotype, but AAV5 consistently had the lowest seroprevalence across the countries studied. AAV5 seropositivity rates were 51.8% in South Africa (n = 56), 46.2% in Russia (n = 91), 40% in Italy (n = 20), 37.2% in France (n = 86), 26.8% in the United States (n = 71), 26.9% in Brazil (n = 26), 28.1% in Germany (n = 89), 29.8% in Japan (n = 84), and 5.9% in the United Kingdom (n = 17). For all serotypes, seropositivity tended to increase with age. Serostatus and antibody titer were generally stable over the 6-month sampling period. As clinical trials of AAV-mediated gene therapies progress, data on the natural prevalence of antibodies against various AAV serotypes may become increasingly important.

Dataset Information

The impact of GPIb? on platelet-targeted FVIII gene therapy in hemophilia A mice with pre-existing anti-FVIII immunity.

Publications

The impact of GPIbα on platelet-targeted FVIII gene therapy in hemophilia A mice with pre-existing anti-FVIII immunity.

Similar Datasets

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