Delayed neutrophil apoptosis in chronic periodontitis patients

Background, aims: Neutrophil cells constitute the first defense barrier against the oral bacterial challenge in the periodontium. Reduction of neutrophils could impair this response against periopathogenic bacteria such as Porphyromonas gingivalis . Our previous work implicates the apoptosis of neutrophils in the pathogenesis of periodontitis. We now demonstrate that granulocyte monocyte-colony stimulating factor (GM-CSF) present in the gingival crevicular fluid (GCF) and secreted during the immune response reduces the apoptosis of neutrophils. Methods: In this study, the presence of GM-CSF and tumor necrosis factor-alpha (TNF-alpha ) in GCF was determined in samples obtained from adult patients with periodontitis and from control subjects with clinically healthy gingiva. GCF was collected for 30 s using Periopaper(R) strips, and cytokines were quantified by ELISA. We used ex vivo culture of gingival tissue biopsies for 2 and 4 days in the presence of GM-CSF. Apoptosis was determined using the terminal TdT-mediated dUTP-biotin nick end labeling (TUNEL) technique, and expression of Bax by immunohistochemistry. Results: The presence of GM-CSF and TNF-alpha was detected in the majority of sites from periodontal patients (83.3% and 63.3%, respectively), presenting a total amount of 27.65 and 42.38 pg, respectively. GM-CSF reduces the neutrophil apoptosis determined by double staining with TUNEL and myeloperoxidase and by a reduction of Bax expression. Conclusions: These findings suggest a novel mechanism by which neutrophils specifically accumulate in adult patients with periodontitis.