Distinct Host Susceptibility and Periodontal Microbiome Shape Oral Neutrophil Priming in Molar– Incisor versus Generalized Periodontitis

The study aimed to compare oral neutrophil (oNeut) functions in molar–incisor pattern periodontitis (MIPP), generalized periodontitis (GP), and periodontally healthy subjects, and to explore how biofilm exposure shapes these functions. oNeut were isolated from healthy, GP, and MIPP volunteers (n=10 per group) and challenged ex vivo with Aggregatibacter actinomycetemcomitans JP2. Reactive oxygen species (ROS) production, cell viability, and cytokine release were quantified post-infection. Separately, healthy oNeut were exposed to de novo biofilms modeling healthy, GP, or MIPP microbiomes, and their functional responses were assessed. Results show that periodontitis patients (GP and MIPP) had higher baseline oNeut counts but exhibited reduced resistance to necrosis and lower ROS output after JP2 challenge than controls; JP2‐stimulated ROS was significantly lower than both HOCl‐treated and naïve controls. MIPP oNeut secreted more TNFα, CCL2, OPG, and RANKL than GP, whereas GP displayed a higher OPG/RANKL ratio. Except for TNFα and IL-1β, all measured mediators were elevated in healthy oNeut versus those from periodontitis groups. Under dysbiotic versus symbiotic biofilm challenge, healthy oNeut produced less ROS but secreted higher TNFα, OPG, and RANKL. Overall, periodontitis patients oNeut exhibit distinct oxidative and cytokine responses to JP2, reflecting host-specific and biofilm-driven priming.