MPO and infection: This difference in activity can result in localized proinflammatory and anti-inflammatory responses around bacterial plaques, which may explain why the infection persists despite high levels of neutrophils at sites of periodontitis.32 In addition to IL-8, gingipains ensure bacterial survival by degrading secretory granule components with antibacterial activity produced by neutrophils, particularly the antimicrobial peptides leucine‒leucine-37 (LL-37) and myeloperoxidase (MPO).33