Oral Polymorphonuclear Neutrophil Phenotype In Edentulous Subjects

Objectives: In dentate subjects it is thought that oral polymorphonuclear neutrophils (oPMNs) originate mainly from the gingival crevices. However, the functional status and potential role of oPMNs in the maintenance of oral health is greatly unknown in edentulous subjects. Therefore, the aim of this study was to characterize oPMN counts, activation status and ROS production in edentulous subjects, compared to dentate subjects.
Methods: oPMNs were purified from oral rinse samples collected from 20 edentulous and 20 dentate subjects. Cell counts were analyzed using a Merck Millipore Muse cell analyzer. Activation status was assessed by cellular expression of CD11b, CD63, and CD66b. Reactive oxygen species production (ROS), with and without stimulation by Fusobacterium nucleatum (Fn), was determined using Dihydrorhodamine 123 and flow cytometry.
Results: oPMN counts were present in edentulous in sizeable numbers (0.7 ± 0.7 x 10⁶/subject), however about 2 fold less compared to dentate subjects (1.5 ± 1.6 x 10⁶/subject, p<0.05). The expression of CD11b, CD63 and CD66b was lower on oPMNs from edentulous (CD11b 0.9 ± 2.3 x 10⁴; CD63 0.8 ± 1.4 x 10⁴; CD66b 2.4 ± 4.7 x 10⁴) compared to dentate subjects (CD11b 6.4 ± 2.9 x 10⁴, p<0.05; CD63 3.1 ± 2.5 x 10⁴, p<0.05; CD66b 10.1 ± 4.8 x 10⁴, p<0.05). In response to Fn stimulation, no upregulation of ROS production was observed in oPMN from edentulous (unstimulated 8.7 ± 10 x 10⁵; Fn 6.9 ± 8.8 x 10⁵, p>0.05), whereas ROS levels were upregulated in oPMNs from dentate (unstimulated 8.4 ± 10 x 10⁵; Fn 23 ± 16 x 10⁵, p<0.05).
Conclusions: In the edentulous, low oPMN numbers were observed. These cells seem more exhausted, with little functional potential when compared with dentate subjects. The reduced oPMN potential might increase the susceptibility of edentulous subjects towards development of oral infections or other diseases.