Background: Chronic periodontitis is highly prevalent and associated with neutrophil-mediated host tissue damage due to neutrophil hyper-activity/reactivity in respect of reactive oxygen species and proteolytic enzyme release. Such collateral tissue damage may be exacerbated by reduced neutrophil tissue transit times and/or delayed apoptosis/impaired efferocytosis. To date, studies have focussed upon neutrophil chemokinesis in periodontitis patients rather than true chemotaxis. Here we employed a novel bridge chamber, the “Insall Chamber”, to investigate directional chemotaxis of PBNs in response to different stimuli in periodontitis patients and matched controls, prior to and following non-surgical treatment.
Method: Neutrophils were isolated from periodontitis sufferers (n=14), prior to and following periodontal therapy, alongside age and gender-matched healthy controls. Migrational chemotaxis was assayed using the Insall chamber, a Zeiss Primovert inverted phase-contrast microscope and real-time video microscopy. PBNs were purified by percoll density centrifugation, simultaneously from patients and controls and exposed to interleukin-8 (IL-8) and formyl-Methionyl-Leucyl-Phenylalanine (fMLP) as chemoattractants. Chemokinesis (speed), velocity and chemotactic index (chemotactic accuracy) were measured from the image stacks and the cell path of each neutrophil tracked was analysed using the Circular Statistics Toolbox from MATLAB.
Result: Neutrophils from periodontitis patients exhibited significantly reduced chemotaxis (p<0.0015), velocity (p<0.0009) and chemokinesis (p<0.0053) relative to healthy controls. Circular statistics confirmed the lack of precision with which periodontitis neutrophils were able to move. Following successful treatment, neutrophil movement in response to IL-8 was no longer significantly different from controls; however defective chemotaxis remained for fMLP.
Conclusion: This pilot study confirms previously reported defects of neutrophil chemokinesis in periodontitis patients and, for the first time defective chemotactic accuracy. Following treatment, accuracy of neutrophil movement was only partially restored.