IRF7 inhibition prevents destructive innate immunity—A target for nonantibiotic therapy of bacterial infections

M Puthia, I Ambite, C Cafaro, D Butler… - Science Translational …, 2016 - science.org
M Puthia, I Ambite, C Cafaro, D Butler, Y Huang, N Lutay, G Rydström, B Gullstrand…
Science Translational Medicine, 2016science.org
Boosting innate immunity represents an important therapeutic alternative to antibiotics.
However, the molecular selectivity of this approach is a major concern because innate
immune responses often cause collateral tissue damage. We identify the transcription factor
interferon regulatory factor 7 (IRF-7), a heterodimer partner of IRF-3, as a target for non–
antibiotics-based therapy of bacterial infections. We found that the efficient and self-limiting
innate immune response to bacterial infection relies on a tight balance between IRF-3 and …
Boosting innate immunity represents an important therapeutic alternative to antibiotics. However, the molecular selectivity of this approach is a major concern because innate immune responses often cause collateral tissue damage. We identify the transcription factor interferon regulatory factor 7 (IRF-7), a heterodimer partner of IRF-3, as a target for non–antibiotics-based therapy of bacterial infections. We found that the efficient and self-limiting innate immune response to bacterial infection relies on a tight balance between IRF-3 and IRF-7. Deletion of Irf3 resulted in overexpression of Irf7 and led to an IRF-7–driven hyperinflammatory phenotype, which was entirely prevented if Irf7 was deleted. We then identified a network of strongly up-regulated, IRF-7–dependent genes in Irf3−/− mice with kidney pathology, which was absent in Irf7−/− mice. IRF-3 and IRF-7 from infected kidney cell nuclear extracts were shown to bind OAS1, CCL5, and IFNB1 promoter oligonucleotides. These data are consistent in children with low IRF7 expression in the blood: attenuating IRF7 promoter polymorphisms (rs3758650-T and rs10902179-G) negatively associated with recurrent pyelonephritis. Finally, we identified IRF-7 as a target for immunomodulatory therapy. Administering liposomal Irf7 siRNA to Irf3−/− mice suppressed mucosal IRF-7 expression, and the mice were protected against infection and renal tissue damage. These findings offer a response to the classical but unresolved question of “good versus bad inflammation” and identify IRF7 as a therapeutic target for protection against bacterial infection.
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