title: Transient siRNA-mediated attenuation of liver expression from an alpha-galactosidase A plasmid reduces subsequent humoral immune responses to the transgene product in mice.
abstract: Hepatocytes are an effective depot for protein production from gene therapy vectors. However, when gene transfer vectors or their delivery induces hepatic inflammation, adaptive immune responses against the transgene product can ensue. In BALB/c mice, hydrodynamic delivery of a CMV-driven plasmid DNA (pDNA) bearing human alpha-galactosidase A (alphagal) to the liver generated antibodies against alphagal. This humoral immune response was more robust in a transgenic knockout for alphagal, the Fabry mouse. The antibody response could be attenuated in both mouse strains by using a promoter more restricted to hepatocytes. In an attempt to reduce further the humoral responses to alphagal, expression from the transgene was attenuated by using siRNA during the period of initial delivery-associated liver inflammation. In both mouse models and with both promoters, codelivering an alphagal siRNA resulted in a 2 log decrease in initial expression that then increased over the next few weeks to levels generated by the pDNA alone. This strategy led to both attenuated antibodies and an immune status approximating "tolerance" to alphagal. Importantly, in the Fabry mouse, an alphagal siRNA together with a hepatocyte-restricted promoter gave minimal anti-alphagal antibodies and profound tolerance, suggesting that such an approach might have clinical utility for genetic diseases.
authors.affiliation: Genzyme Corporation, 31 New York Avenue, Framingham, MA 01701, USA.
authors.forename: Qiuming
authors.initials: Q
authors.lastname: Chu
authors.forename: Macy
authors.initials: M
authors.lastname: Joseph
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Przybylska
authors.forename: Nelson S
authors.initials: NS
authors.lastname: Yew
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Scheule
mesh_terms: D000818:Animals; D002450:Cell Communication; D004195:Disease Models, Animal; D000795:Fabry Disease; D015870:Gene Expression / Q000187:drug effects; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D005822:Genetic Vectors; D022781:Hepatocytes / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000494:pharmacology* / Q000627:therapeutic use; D014162:Transfection; D000519:alpha-Galactosidase / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering; D000519:alpha-Galactosidase