Refractory Periodontitis Population Characterized by a Hyperactive Oral Neutrophil Phenotype

Abstract

Neutrophils, in addition to being the primary protective component of the innate immune system, also contribute to periodontal destruction through production of reactive oxygen species (ROS), which cause damage to connective tissues and extracellular matrix after neutrophil activation. We have previously shown that hyperactive neutrophils are present in peripheral blood samples of patients diagnosed with refractory periodontitis. To test the hypothesis that oral neutrophil hyperactivity is related to periodontal disease severity, we used a flow cytometric approach to isolate and analyze oral neutrophil ROS (oROS) production in a refractory periodontal disease patient population. Oral rinse samples and venous blood were obtained from 13 patients diagnosed with refractory periodontitis. After isolation of neutrophils from both samples, dihydrorhodamine 123 was used as a fluorescent probe for phorbol 12-myristate 13-acetate-mediated ROS production as assessed through flow cytometry. For each patient, oROS production levels were expressed as a percentage of their baseline to maximal peripheral blood neutrophil ROS production range. Two distinct groups of refractory patients were identified based on levels of phorbol 12-myristate 13-acetate-stimulated oROS production. The patient group with high oROS production had significantly more clinical attachment loss (AL) compared to the patient group with low oROS production. Our findings demonstrate that a group of refractory patients with increased clinical AL present a hyperactive oral neutrophil phenotype characterized by increased potential for ROS production. Identification of this exaggerated oral neutrophil phenotype could allow clinicians to identify which patients are more susceptible to rapid disease progression.