Epitope-diverse autoantibodies induce neutrophil-epithelial niches driving kidney injury in ANCA-associated glomerulonephritis.

Autoantibody-mediated inflammation drives tissue injury in autoimmune diseases, yet how pathogenic antibodies evoke local immune activation remains poorly understood. Here, we show that spatially organized neutrophil-epithelial niches contribute to kidney injury in myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody-associated glomerulonephritis. Single-cell-resolved spatial transcriptomics of treatment-naïve patient kidney biopsies identified early-phase inflammatory niches enriched with HAVCR1+ injured proximal tubular epithelial cells, neutrophils, lymphocytes, and TREM2+ macrophages. Injured epithelial cells expressed chemokines including CXCL6 and CXCL16, defining a microenvironment associated with local immune cell accumulation. Neutrophils within these niches were characterized by transcriptional programs enriched for type II interferon and Fcγ receptor (FcγR)-related signaling. Mechanistically, combinations of monoclonal anti-MPO antibodies recognizing distinct epitopes enhanced neutrophil activation and induced pauci-immune crescentic glomerulonephritis in mice, recapitulating key aspects of epithelial injury observed in human kidneys. One-armed anti-MPO antibodies engineered to minimize FcγR engagement ameliorated kidney injury in mice. Together, these findings identify pathogenic neutrophil-epithelial niche formation as a driver of autoimmune kidney injury.