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.
Walker
Wendy E
WE
Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA. wendy.walker@yale.edu
Booth
Carmen J
CJ
Goldstein
Daniel R
DR
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