title: Polyinosinic acid blocks adeno-associated virus macrophage endocytosis in vitro and enhances adeno-associated virus liver-directed gene therapy in vivo.
abstract: Adeno-associated virus serotype 8 (AAV8) has been demonstrated to be effective for liver-directed gene therapy in humans. Although hepatocytes are the main target cell for AAV8, there is a loss of the viral vector because of uptake by macrophages and Kupffer cells. Reducing this loss would increase the efficacy of viral gene therapy and allow a dose reduction. The receptor mediating this uptake has not been identified; a potential candidate seems the macrophage scavenger receptor A (SR-A) that is involved in the endocytosis of, for instance, adenovirus. In this study we show that SR-A can mediate scAAV8 endocytosis and that blocking it with polyinosinic acid (poly[i]) reduces endocytosis significantly in vitro. Subsequently, we demonstrate that blocking this receptor improves scAAV-mediated liver-directed gene therapy in a model for inherited hyperbilirubinemia, the uridine diphospho-glucuronyl transferase 1A1-deficient Gunn rat. In male rats, preadministration of poly[i] increases the efficacy of a low dose (1×10¹¹ gc/kg) but not of a higher dose (3×10¹¹ gc/kg) scAAV8-LP1-UT1A1. Administration of poly[i] just before the vector significantly increases the correction of serum bilirubin in female rats. In these, the effect of poly[i] is seen by both doses but is more pronounced in the females receiving the low vector, where it also results in a significant increase of bilirubin glucuronides in bile. In conclusion, this study shows that SR-A mediates the endocytosis of AAV8 in vitro and in vivo and that blocking this receptor can improve the efficacy of AAV-mediated liver-directed gene therapy.
authors.affiliation: Department of Gastroenterology & Hepatology and Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, University of Amsterdam, 1105 BK Amsterdam, The Netherlands. r.vandijk@amc.uva.nl
authors.forename: Remco
authors.initials: R
authors.lastname: van Dijk
authors.forename: Paula S
authors.initials: PS
authors.lastname: Montenegro-Miranda
authors.forename: Christel
authors.initials: C
authors.lastname: Riviere
authors.forename: Ronald
authors.initials: R
authors.lastname: Schilderink
authors.forename: Lysbeth
authors.initials: L
authors.lastname: ten Bloemendaal
authors.forename: Jacqueline
authors.initials: J
authors.lastname: van Gorp
authors.forename: Suzanne
authors.initials: S
authors.lastname: Duijst
authors.forename: Dirk R
authors.initials: DR
authors.lastname: de Waart
authors.forename: Ulrich
authors.initials: U
authors.lastname: Beuers
authors.forename: Hidde J
authors.initials: HJ
authors.lastname: Haisma
authors.forename: Piter J
authors.initials: PJ
authors.lastname: Bosma
mesh_terms: D000818:Animals; D001663:Bilirubin / Q000097:blood; D016466:CHO Cells; D002460:Cell Line; D003412:Cricetulus; D003414:Crigler-Najjar Syndrome / Q000235:genetics / Q000628:therapy; D000229:Dependovirus / Q000276:immunology*; D004195:Disease Models, Animal; D004705:Endocytosis / Q000187:drug effects*; D005260:Female; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D014453:Glucuronosyltransferase / Q000235:genetics; D057809:HEK293 Cells; D022781:Hepatocytes / Q000821:virology; D006801:Humans; D007728:Kupffer Cells / Q000187:drug effects / Q000276:immunology*; D008099:Liver / Q000276:immunology / Q000378:metabolism; D008297:Male; D011069:Poly I / Q000378:metabolism*; D051381:Rats; D051117:Scavenger Receptors, Class A / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D014161:Transduction, Genetic
chemical_list: D051117:Scavenger Receptors, Class A; D011069:Poly I; D014453:Glucuronosyltransferase; D001663:Bilirubin