Oral polymorphonuclear neutrophil characteristics in relation to oral health: a cross-sectional, observational clinical study

Abstract

Polymorphonuclear neutrophils (PMNs) have a major role in the innate immune system. However, little is known about PMN contribution in relation to oral health. The objective of this study was to investigate the numbers and functional characteristics of oral PMNs (oPMNs) compared with circulatory PMNs (cPMNs). Oral rinse and venous blood samples were obtained from 268 systemically and orally healthy volunteers in a cross-sectional observational study. PMN counts, cell cycle analysis and cellular activation state were investigated. Also, reactive oxygen species (ROS) production was analyzed, with and without bacterial stimulation (Fusobacterium nucleatum). In males, 1.2 × 106±1.0 × 106 oPMNs were collected, and showed a tendency to correlate with the levels of gingival bleeding (r=0.215, P=0.008). Comparable oPMNs counts were found among females (1.0 × 106±0.7 × 106). More late-stage apoptotic/necrotic cells were found among the oPMNs (53.1%) compared with the cPMNs (8.5% P<0.001). Without additional stimulation, oPMNs were more activated than cPMNs, as indicated by higher expression of CD11b, CD63 and CD66b, and higher constitutive ROS levels (P<0.001). Notably, in response to bacterial stimulation, oPMNs released comparable ROS levels as cPMNs (P=0.042). In conclusion, this study provides data on viable oPMNs showing high levels of activation in orally and systemically healthy individuals, free of apparent caries lesions and periodontal disease. These data suggests that although the oPMNs are in a more mature stage of their life cycle compared with the cPMNs, oPMNs are still responsive to stimulation, which indicates their functional potential and possible contribution to a healthy oral ecosystem.

Identification of inflammatory response patterns in experimental gingivitis studies

“…Moreover, the gingival inflammation background – as indicated by the level of gingival inflammation measured at the time of eligibility assessment (day −14) – was shown to be associated with the ‘fast’ but not with the ‘slow’ gingival response pattern. This may indicate that a ‘fast’ response could be a result of priming, and it is possible that, in ‘fast’ responders, neutrophils (which are essential components of the primary innate immune response) may be primed by exposure to the oral biofilm . Hence, a de novo exposure to the oral biofilm might rapidly activate primed neutrophils to respond, and so explain our observations .…”

Neutrophil Subsets in Periodontal Health and Disease: A Mini Review

“…Another group of researchers led by Nicu and Loos, have also been investigating oral neutrophils by their surface markers (19). They described that in oral neutrophils from healthy donors without additional stimulation, these cells were more activated than circulatory neutrophils, as indicated by higher expression of CD11b, CD63, and CD66b, and elevated constitutive ROS release.…”

Oral inflammatory load: Neutrophils as oral health biomarkers

“…Across the entire gastrointestinal tract, PMNs serve to inactivate bacteria found in the lumen and prevent bacterial transit across the epithelium 19 . PMNs within the oral cavity act as a barrier within the gingival crevice, preventing the passage of bacteria deeper into subjacent gingival connective tissue, subsequent infection, and limiting damage to the periodontium 6 .…”

“…The potential use of oPMN counts as a screening tool for periodontitis is coming at a time when research concerning the immunophysiologic characteristics of oPMNs is demonstrating the potential existence of peripheral and tissue‐resident neutrophil subsets in periodontal health and disease 12,19,72,73 . This suggests the potential of using both the quantification of oPMNs and the various peripheral and oPMN population subsets to provide even greater insight into establishing the diagnosis and grading the severity of periodontitis.…”