Neutrophils from periodontitis patients exhibit defective chemotaxis

Objective: Periodontitis is one of the most common infectious-inflammatory diseases of humans with prevalence for severe disease of 10-15% of adults worldwide (WHO). Periodontitis is caused by dysregulated inflammatory-immune responses to bacteria that adhere to and colonise the teeth. If left untreated chronic inflammation results, eventually leading to tooth loss. Neutrophils, the most prevalent innate immune cell present in blood, are the first line of defence during microbial infections. The recruitment of neutrophils to and from the site of infection is an essential step in innate and acquired immunity. Previous studies claim to have demonstrated defective chemotaxis in periodontitis sufferers using bridge chambers; however such chambers measure chemokinesis rather than chemotaxis, where accuracy and velocity of directional movement should be measured. We therefore analysed directional chemotaxis in response of peripheral blood neutrophils to different stimuli in periodontitis patients and unaffected controls, using a novel chamber, the “Insall chamber”.

Method: Neutrophils were isolated from periodontitis sufferers (n = 10) alongside gender and age-matched healthy controls. Migrational chemotaxis was assayed using the Insall bridge chamber with neutrophils exposed to interleukin-8 (IL-8) and formyl-Methionyl-Leucyl-Phenylalanine (fMLP). Speed (chemokinesis), velocity and chemotactic index (chemotactic accuracy) were measured from the image stacks and the cell path of each neutrophil tracked was analysed using a circular statistics tool box from MATLAB. 

Result: Neutrophils from periodontitis sufferers showed defective chemotaxis and velocity and diminished speed compared to those of healthy controls upon exposure to physiologically relevant chemoattractants. Circular statistical results also confirmed the lack of precision with which neutrophils isolated from periodontitis patients were able to move. 

Conclusion: This pilot study confirms previous studies that identify defective chemokinesis in neutrophils from periodontitis patients compared to gender and age-matched controls. We also show, for the first time, defects in velocity and accuracy of neutrophil movement using better defined cell movement parameters.