The impact of type II diabetes and chronic periodontal disease on peripheral blood neutrophil apoptosis

Abstract

Aims: to test the hypothesis that peripheral blood neutrophils (PMN) exhibit delayed spontaneous apoptosis in individuals with type 2 Diabetes, and that the delay is further exacerbated in individuals who co-express chronic periodontitis. Materials and methods: 73 individuals were enrolled, including those with type 2 diabetes (T2DM) (n=16), chronic periodontitis (CP) (n=15), diabetics with chronic periodontitis (T2DM+CP) (n=21) and healthy volunteers (n=21). PMN apoptosis was determined by flow cytometry using TUNEL and Annexin V assays. Caspase 3, 8 and 9 activity was measured by colorimetric assay. PMN surface death receptor quantification was performed by flow cytometry staining with fluorescence conjugated anti-CD120a (TNFR1) and anti- CD95 (FasR) antibody. Inflammatory biomarker analyses of serum samples were performed using multiplexed sandwich immunoassays. Results: In healthy volunteers, individuals with T2DM, CP and T2DM+CP, spontaneous PMN apoptosis observed at 12 hours reached 85.3% ± 3.1, 67.3% ± 3.9, 62.9% ± 3.5 and 62.5% ± 5.4, respectively (p<0.05 ). Caspase-3 activity was significantly reduced in individuals with T2DM and T2DM+CP (p<0.05), when compared to healthy volunteers. Caspase-8 activity was also significantly decreased in CP and T2DM+CP (p<0.05), associated with reduced cell surface Fas receptor, TNF receptors and Fas ligand serum levels. Glucose alone was not observed to effect PMN apoptosis; concurrent incubation with the RAGE agonist S-100B induced a significant PMN apoptosis (p<0.05). Conclusion: These data support the premise that the inhibition of PMN apoptosis in individuals with T2DM occurs through an AGE/RAGE ligand/receptor mediated interaction.