Treatment of anti-myeloperoxidase glomerulonephritis using recombinant deoxyribonuclease I is enhanced by adeno-associated virus gene therapy

Extracellular DNA (ecDNA) released from injured and dying cells powerfully induces injurious inflammation. In this study we show ecDNA renal presence in patients and experimental mice with myeloperoxidase anti-neutrophil cytoplasmic antibody-associated glomerulonephritis (MPO-ANCA GN). Twice daily administration of intravenous DNase I (ivDNase I) in two models of anti-MPO GN was effective at reducing glomerular deposition of ecDNA, histological injury, leukocyte infiltration and NETosis. Comprehensive investigation into DNase I modes of action revealed the enzyme reduced lymph node DC numbers and their activation status, resulting in decreased frequency of MPO-specific CD4 effector T cells (IFN-gamma and IL17A producing), reductions in dermal anti-MPO delayed type hypersensitivity responses and increased frequency of MPO-specific T regulatory cells. Renal expression of inflammatory chemokines were also decreased. To overcome the translational obstacle of the short half-life of DNase I (<5 hours), we tested an adeno-associated viral vector encoding DNase I in one of the models. Along with the endpoint changes described above, a single vector treatment also enhanced therapeutic benefit as seen by reductions in MPO-ANCA and albuminuria. These results indicate ecDNA is a potent driver of anti-MPO GN and that DNase I is a potential therapeutic that can be delivered using gene technology.