Increased gene copy number of <i>DEFA1/DEFA3</i> worsens sepsis by inducing endothelial pyroptosis.

Abstract

Sepsis claims an estimated 30 million episodes and 6 million deaths per year, and treatment options are rather limited. Human neutrophil peptides 1-3 (HNP1-3) are the most abundant neutrophil granule proteins but their neutrophil content varies because of unusually extensive gene copy number polymorphism. A genetic association study found that increased copy number of the HNP-encoding gene <i>DEFA1/DEFA3</i> is a risk factor for organ dysfunction during sepsis development. However, direct experimental evidence demonstrating that these risk alleles are pathogenic for sepsis is lacking because the genes are present only in some primates and humans. Here, we generate <i>DEFA1/DEFA3</i> transgenic mice with neutrophil-specific expression of the peptides. We show that mice with high copy number of <i>DEFA1/DEFA3</i> genes have more severe sepsis-related vital organ damage and mortality than mice with low copy number of <i>DEFA1/DEFA3</i> or wild-type mice, resulting from more severe endothelial barrier dysfunction and endothelial cell pyroptosis after sepsis challenge. Mechanistically, HNP-1 induces endothelial cell pyroptosis via P2X7 receptor-mediating canonical caspase-1 activation in a NLRP3 inflammasome-dependent manner. Based on these findings, we engineered a monoclonal antibody against HNP-1 to block the interaction with P2X7 and found that the blocking antibody protected mice carrying high copy number of <i>DEFA1/DEFA3</i> from lethal sepsis. We thus demonstrate that <i>DEFA1/DEFA3</i> copy number variation strongly modulates sepsis development in vivo and explore a paradigm for the precision treatment of sepsis tailored by individual genetic information.