Levels of interferon-gamma and transcription factor T-bet in progressive periodontal lesions in patients with chronic periodontitis

Background: Periodontitis is an infection with an episodic pattern of tissue-support destruction. During the generation of a primary CD4 ⁺ T helper 1 (Th1) response, interferon-gamma (IFN-γ) acts as a positive regulator by selectively inducing Th1 differentiation through increased transcription of T-bet. The aims of this work were to determine IFN-γ levels in samples of gingival crevicular fluid (GCF) and to determine IFN-γ and transcription factor T-bet expression in gingival tissue from patients undergoing the progression of chronic periodontitis. Methods: One hundred six patients with moderate or advanced chronic periodontitis were selected. Periodontitis was characterized by at least six sites with probing depth ≥5 mm, clinical attachment loss ≥3 mm, and radiographic bone loss. Periodontitis progression was determined by the tolerance method. GCF was collected using a paper strip, and enzyme-linked immunosorbent assay was performed to determine the total amount of IFN-γ. Gingival biopsies were obtained from patients for real-time reverse transcription-polymerase chain reaction to determine IFN-γ and T-bet expression. Statistical analysis was performed using statistical software. Data were expressed as subject means ± SD. The χ ² and Student t tests were used. Results: The total amount and concentration of cytokine IFN-γ were significantly higher in active sites than in inactive sites (99.90 versus 68.90 pg; P = 0.03; 106.62 pg/mg versus 75.64 pg/mg, P = 0.04, respectively). Active sites showed a significantly lower Δ cycle threshold (Ct) of IFN-γ than inactive sites (P = 0.04), whereas the expression of transcription factor T-bet was increased 1.42-fold in active sites compared to inactive sites. Conclusion: The total amount and concentration of cytokine IFN-γ in GCF samples and transcription factor T-bet expression were increased in progressive periodontal lesions in patients with chronic periodontitis.