TLR9 and IRF3 cooperate to induce a systemic inflammatory response in mice injected with liposome:DNA.
Liposome:DNA is a promising gene therapy vector. However, this vector can elicit a systemic inflammatory response syndrome (SIRS). Prior reports indicate that liposome:DNA vectors activate Toll-like receptor (TLR)9. We hypothesized that liposome:DNA vectors also activate the cytosolic DNA-sensing pathway, which signals via interferon (IFN) regulatory factor (IRF)3. To test this, we treated dendritic cells (DCs) with liposome:DNA in vitro and found that IRF3 was phosphorylated independent of TLR9. To test the contribution of this pathway in vivo, we injected a liposome:DNA vector into wild-type (WT), TLR9-knockout (KO), IRF3-KO, and TLR9-IRF3-double-KO (DKO) mice. WT mice exhibited a systemic inflammatory response, evidenced by elevations in serum cytokines, serum enzyme changes indicating organ damage, hypothermia, and mortality. The cytokine response was reduced in TLR9-KO, IRF3-KO, and TLR9-IRF3-DKO mice and all three groups survived. We found that IFN-gamma-KO mice that receive liposome:DNA had a reduced cytokine response and 100% survival. CD11c(+) and NK1.1(+) cells produced IFN-gamma and depleting CD11c(+) cells reduced the cytokine response in mice injected with liposome:DNA. These findings may facilitate the development of immunologically inert gene therapy vectors and may provide general insight into the mechanisms of SIRS.
Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA. wendy.walker@yale.edu
Wendy E
WE
Walker
Carmen J
CJ
Booth
Daniel R
DR
Goldstein
D000818:Animals; D018845:CD11 Antigens / Q000276:immunology; D016207:Cytokines / Q000276:immunology; D004247:DNA / Q000008:administration & dosage / Q000276:immunology*; D003713:Dendritic Cells / Q000276:immunology; D005822:Genetic Vectors / Q000008:administration & dosage / Q000276:immunology*; D050838:Interferon Regulatory Factor-3 / Q000235:genetics / Q000276:immunology*; D007371:Interferon-gamma / Q000276:immunology; D008081:Liposomes; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018746:Systemic Inflammatory Response Syndrome / Q000276:immunology*; D051217:Toll-Like Receptor 9 / Q000235:genetics / Q000276:immunology*
D018845:CD11 Antigens; D016207:Cytokines; D050838:Interferon Regulatory Factor-3; C494233:Irf3 protein, mouse; D008081:Liposomes; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D007371:Interferon-gamma; D004247:DNA