title: Unique Roles of TLR9- and MyD88-Dependent and -Independent Pathways in Adaptive Immune Responses to AAV-Mediated Gene Transfer.
abstract: The immune system represents a significant barrier to successful gene therapy with adeno-associated viral (AAV) vectors. In particular, adaptive immune responses to the viral capsid or the transgene product are of concern. The sensing of AAV by toll-like receptors (TLRs) TLR2 and TLR9 has been suggested to play a role in innate immunity to the virus and may also shape subsequent adaptive immune responses. Here, we investigated the functions of TLR2, TLR9 and the downstream signaling adaptor MyD88 in antibody and CD8+ T-cell responses. Antibody formation against the transgene product occurred largely independently of TLR signaling following gene transfer with AAV1 or AAV2 vectors, whereas loss of signaling through the TLR9-MyD88 pathway substantially reduced CD8+ T-cell responses. In contrast, MyD88 (but neither of the TLRs) regulated antibody responses to capsid. B cell-intrinsic MyD88 was required for the formation of anti-capsid IgG2c independently of vector serotype or route of administration. However, MyD88(-/-) mice instead produced anti-capsid IgG1 that emerged with delayed kinetics but nonetheless completely prevented in vivo readministration. We conclude that there are distinct roles for TLR9 and MyD88 in promoting adaptive immune responses to AAV-mediated gene transfer and that there are redundant MyD88-dependent and MyD88-independent mechanisms that stimulate neutralizing antibody formation against AAV.
authors.affiliation: Division of Cellular and Molecular Therapy, Department of Pediatrics, University of Florida, Gainesville, Fla., USA.
authors.forename: Geoffrey L
authors.initials: GL
authors.lastname: Rogers
authors.forename: Masataka
authors.initials: M
authors.lastname: Suzuki
authors.forename: Irene
authors.initials: I
authors.lastname: Zolotukhin
authors.forename: David M
authors.initials: DM
authors.lastname: Markusic
authors.forename: Laurence M
authors.initials: LM
authors.lastname: Morel
authors.forename: Brendan
authors.initials: B
authors.lastname: Lee
authors.forename: Hildegund C J
authors.initials: HC
authors.lastname: Ertl
authors.forename: Roland W
authors.initials: RW
authors.lastname: Herzog
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D000229:Dependovirus / Q000235:genetics / Q000276:immunology*; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000276:immunology*; D014161:Transduction, Genetic
chemical_list: D007074:Immunoglobulin G; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9