Th2 cells and the IFN-γ R1 subunit in early and advanced experimental periodontitis in rats; an immunohistochemical study

Aim: To evaluate the involvement of Th2 cells in different periods of the active phase of experimental periodontal disease and expression of the R1 subunit of the receptor for IFN-γ during the early and advanced progression of the disease. Methods: Experimental periodontitis was induced in 30 male Wistar rats by placing cotton ligatures around the mandibular first molars. The rats were then randomly assigned into two groups: G1=15 and G2=15, in group G1, ligatures were maintained for 2 days, a period that corresponds to the initial stage of periodontal disease in rats, in G2 ligatures were left for 15 days, a period that corresponds to the advanced stage of periodontal disease. The contra-lateral teeth served as controls (unligated). An immunohistochemical investigation of the gingival tissue was performed to detect the presence of the Th2 specific transcription factor (GATA3). Results: Light microscopy analysis revealed a decreased expression of GATA-3-positive cells when bone loss progressed. IFN-γ R1 was detected at an early stage during the active phase of disease, but the expression of positive cells remained unaltered during the remaining period of the study. Conclusions: These results indicate that the Th2 response may have a protective role during the pathogenesis of experimental periodontal disease, and that the IFN-γ R1 subunit may not be associated with periodontal disease progression.

Keywords
rats; periodontal diseases; Th1 cells; Th2 cells; cytokines; immunohistochemistry