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 define the role of ecDNA in systemic vasculitis affecting the kidney, using human kidney biopsies and murine models of 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 reduced glomerular deposition of ecDNA, histological injury, leukocyte infiltration and NETosis. Comprehensive investigation into DNase I modes of action revealed that after exposure to MPO, DNase I reduced lymph node DC numbers and their activation status, resulting in decreased frequency of MPO-specific CD4 effector T cells (IFN-{gamma}, and IL-17A producing), and reductions in dermal anti-MPO delayed type hypersensitivity responses. 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 (vec-DNase I). The method of DNase I delivery was more effective, as in addition to the histological and anti-inflammatory changes described above, a single vector treatment also reduced circulating MPO-ANCA titers 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.