Abstract: PURPOSE: To compare the expression of CD4⁺ T cells in mice periodontitis induced by two periodontal pathogen strains, and evaluate the role of CD4⁺ T cells in periodontitis. METHODS: Twelve C57BL/6 mice were divided into 3 groups at random including sham-infected, Porphyromonas gingivalis (P. gingivalis) W83-infected and P. gingivalis ATCC 33277-infected groups. All mice were sacrificed at the 4th week after the last infection. The analysis of alveolar bone resorption and the examination of histological staining were performed. The population of CD4⁺ T cells in the gingivae and the cervical lymph nodes (CLNs) were analyzed by flow cytometry. SPSS 11.0 software package was used for statistical analysis. RESULTS: The levels of alveolar bone resorption were significantly high in both P. gingivalis W83-infected and P. gingivalis ATCC 33277-infected mice compared to sham-infected mice. Histological staining showed that the loss of periodontal attachment and osteoclasts-mediated alveolar bone resorption were found in both P. gingivalis W83-infected and P. gingivalis ATCC 33277-infected mice. Moreover, the periodontal destruction was severer in P. gingivalis W83-infected mice than in P. gingivalis ATCC 33277-infected mice. Flow cytometry showed that the percentage of CD4⁺ T cells in the gingivae and CLNs in both P. gingivalis W83-infected and P. gingivalis ATCC 33277-infected mice were significantly higher than that in sham mice, and P. gingivalis W83-infected mice had a higher percentage of CD4⁺ T cells compared to P. gingivalis ATCC 33277-infected mice. CONCLUSIONS: The population of CD4⁺ T cells participates in the pathogenesis of periodontitis, and closely correlates with the periodontal destruction induced by periodontal pathogen infection.

Key words: CD4+ T cell, Periodontitis, Animal model