Detection of Protein Carbonylation in Gingival Biopsies from Periodontitis Patients with or Without Diabetes Mellitus-A Pilot Study.

Background: Protein carbonylation is an irreversible post-translational modification that is considered indicative of oxidative damage. Objective: The purpose of the study was to examine by an immunohistochemical method for the first time the extent and localization of protein carbonylation in biopsies of gingiva from periodontitis patients with or without diabetes mellitus (DM). Methods: These were processed for immunohistochemical staining of the carbonylated proteins, using the ENVISIOM FLEX Mini Kit, high pH, and anti-dinitrophenyl (DNP) antibody, a marker of oxidative damage to a given protein. The extent of protein carbonylation was semi-quantitatively estimated and evaluated by calculation of the Allred score (percentage of stained cells × intensity of staining). Results: The biopsies from periodontitis patients with diabetes mellitus (DM) exhibited higher staining scores as per the percentage of positively stained cells than the biopsies from patients with only periodontitis (means of 49.2 and 16.7, respectively), the difference being statistically significant (p = 0.036). The same trend was observed in the case of the combination of the above with the intensity of staining (score parameter) as well (means of 59.6 and 20.8, p = 0.036, respectively). Conclusions: An immunohistochemical method with the novelty of utilization for the first time of the anti-dinitrophenyl (DNP) antibody in gingival tissues was introduced and showed efficacy in detecting protein carbonylation indicative of oxidative stress and its impact in the pathogenesis of these two prevalent diseases of periodontitis and diabetes mellitus.