Salivary DNA, lipid, and protein oxidation in nonsmokers with periodontal disease

Abstract

Reactive oxygen species (ROS) are implicated in the destruction of the periodontium during periodontitis. The imbalance in oxidant activity may be a key factor. The aim of this paper is to determine whether periodontitis is associated with increased oxidative damage to DNA, lipids, and proteins and modification of total antioxidant capacity (TAC) in saliva. Saliva was collected from 58 periodontitis patients and 234 healthy controls, all nonsmokers. Periodontal disease status was characterized using the Community Periodontal Index of Treatment Needs (CPITN). Assays for 8-OHdG (ELISA), 8-epi-PGF2alpha (ELISA), and total protein carbonyls (ELISA), and oxy-blotting (Western)/mass spectrometry were performed to quantify oxidative damage to nucleic acids, lipids, total and individual proteins, respectively, in whole nonstimulated saliva. Salivary TAC was measured by inhibition of ABTS oxidation by metmyoglobin. We observed (i) significantly higher levels of 8-OHdG, 8-epi-PGF2alpha, and carbonylated proteins in saliva of periodontal patients as compared with controls (P=0.0003, <0.0001 and <0.0001); (ii) 8-OHdG, 8-epi-PGF2alpha, and carbonylated proteins were independently negatively associated with CPITN (P=0.004, 0.02, and <0.0001); (iii) a positive correlation between salivary TAC and periodontal disease status in the study group (P<0.0001); and (iv) specific oxidation of transferrin, human IgG1 heavy chain fragment, and salivary amylase in periodontitis. Periodontal disease is associated with increased oxidative modification of salivary DNA, lipids, and proteins. Augmented salivary total antioxidant capacity may represent an adaptive response to oxidative stress. Salivary amylase, transferrin, and human IgG1 heavy chain fragments are particularly prone to enhanced oxidation in periodontitis.