Immune System Regulation of Transgene Expression in the Brain 2: Differential Increase of mRNAs Encoding for Interferon-Regulated, Chemokine, and T-Cell Genes during Either Innate Acute or Chronic Systemic Adaptive Immune Responses to First Generation Ade

ZIRGER; BARCIA; LIU; PUNTEL; SITIA; GUIDOTTI; MITCHELL; CAMPBEL; CASTRO; LOWENSTEIN

Minneapolis, MN, USA

Congreso; American Society of Gene Therapy; 2004

1019. Immune System Regulation of TransgeneExpression in the Brain 2: Differential Increase ofmRNAs Encoding for Interferon-Regulated,Chemokine, and T-Cell Genes during EitherInnate Acute or Chronic Systemic AdaptiveImmune Responses to First GenerationAdenoviral VectorsJeffrey M. Zirger,1 Carlos Barcia,1 Chunyan Liu,1 MarianaPuntel,1 Giovanni Sitia,4 Luca Guidotti,2,4 Ngan Mitchell,2 IainCampbell,2,3 Maria G. Castro,1 Pedro R. Lowenstein.11Gene Therapeutics Research Institute, Cedars-Sinai MedicalCenter, Los Angeles, CA; 2The Scripps Research Institute, LaJolla, CA; 3University of Sydney, Sydney, Australia; 4San RaffaeleScientific Institute, Milan, Italy.Gene therapy approaches using first generation adenoviral (Ad)vectors have shown the ability to produce long-term transgeneexpression in the brain in animal models. The use of these firstgeneration vectors is limited, however, by peripheral immunizationthat generates an anti-adenoviral immune response. This responseis characterized by inflammation in the brain and the eventualelimination of the encoded transgene expression. The following studywas designed to determine the cellular and molecular effectorsinvolved in this immune response in mice. Both naïve and immunizedanimals were injected with increasing doses of first generation Advectors carrying the gene for beta-galactosidase (b-gal) or thymidinekinase (TK). RNAse protection assays (RPAs) were performed onRNA extracted from homogenized brain tissue using probe sets todetermine the expression of interferon (IFN) gene families, IFNregulatedgenes, chemokines, as well as markers of T-cells (CD3,CD4 and CD8), and macrophages (F4/80). The results of this workindicate that the naïve brain responds rapidly to the injection of Advectors by the induction of a variety of cellular effector mechanisms,including expression of the IFN-regulated genes, TGTP, OAS, andIRF-1, and the chemokines MCP-3, MIP-1b,MCP-1, IP-10,RANTES. A threshold level for injection of 1x107-1x108 infectiousresponses were detected. The time course experiments showed theseresponses to be transient, with most mRNAs returning to basallevels by day 14 post-injection into the brain. To study themechanisms of the adaptive immune response, animals previouslyinjected with RAd in the brain, were systemically immunized againstadenovirus. In immunized animals there was an important increasein T-cell markers CD3, CD4, and CD8, while there was no increaseof the monocyte marker F4/80. Expression of IFN-regulated geneswas also increased. A different set of chemokines was elevated inthe case of the adaptive immune response when compared to thoseseen in the early innate responses. These studies indicate that acuteinnate inflammatory responses in mice are dose dependent, transient,and mediated by an increase in interferon signaling and chemokineinduction. The systemic immune response demonstrates a longertime course, and is mediated by CD4 and CD8 T-cells, andaccompanied by an increase in interferon signaling, mainly due tointerferons a and b, and possibly a smaller contribution of interferong, and TNF.