Distinct Oral Neutrophil Subsets Define Health and Disease States

Neutrophils exit the vasculature and swarm to sites of inflammation and infection. Neutrophils are also actively recruited to the healthy periodontium without eliciting clinical signs of inflammation, suggesting a unique immune surveillance neutrophil function. We hypothesized that oral neutrophils in the healthy periodontium exist in a â para-inflammatoryâ state that allows neutrophils to symbiotically interact with the commensal oral microflora. Using the principles of immunophenotyping, we identified four distinct neutrophil subsets: resting circulatory neutrophils, two para-inflammatory and one pro-inflammatory tissue neutrophil phenotypes in the absence and presence of chronic inflammation, respectively. This work is the first to comprehensively characterize healthy oral neutrophils and identity the para-inflammatory neutrophil phenotype, thereby demonstrating that not all neutrophils trafficking through periodontium are fully activated. In addition to establishing possible diagnostic and treatment monitoring biomarkers, the oral tissue neutrophil phenotype model builds on existing literature suggesting that the healthy periodontium may be in a para-inflammatory state.M.Sc