Peripheral memory T-cell profile is modified in patients undergoing periodontal management

Abstract

Aims: T-cells are known to have a role in periodontitis, however, the effect of periodontal therapy on peripheral memory T-cells is unclear. This study evaluated variation in peripheral memory T-cells and red complex bacteria in sub-gingival plaque in patients undergoing periodontal management.

Methods: Peripheral blood mononuclear cells and sub-gingival plaque were collected from 54 periodontitis patients at baseline, 3-, 6- and 12-months post-therapy and 40 healthy controls. Periodontitis patients were divided into treatment outcome (TxO) groups based on prevalence of sites with probing depth ≥5 mm as good (<10% of sites), moderate (10-20%) or poor (>20%) at study conclusion. Naïve (T_N -CCR7⁺ CD45RA⁺ ), central memory (T_CM -CCR7⁺ CD45RA^- ), effector memory (T_EM -CCR7^- CD45RA^- ) and effector memory T-cells re-expressing CD45RA (T_EMRA -CCR7^- CD45RA⁺ ) were phenotyped using flow cytometry in CD4⁺ , CD8⁺ , CD4⁺ CD8⁺ and CD4^- CD8^- T-cells and red complex bacteria were quantified using qPCR.

Results: At baseline, periodontitis subjects had significantly greater mean probing depths and Porphyromonas gingivalis proportions, lower T_N but higher CD4⁺ T_CM , CD8⁺ T_CM , CD4⁺ CD8⁺ T_EM and CD4^- CD8^- T_EM cell proportions compared to health. Periodontal therapy decreased mean probing depths, P. gingivalis proportions, T_EM and CD4⁺ and CD8⁺ T_CM cells, but increased T_N and CD4⁺ and CD8⁺ T_EMRA cells. The T-cell profile in the good TxO group showed therapy-related changes in CD4⁺ T_EM , and CD8⁺ T_N and T_EM cells, whereas, no changes were observed in the poor TxO group.

Conclusion: Management and the reduction in red complex bacteria were associated with changes in peripheral memory T-cells in periodontitis.

Keywords: T-lymphocytes; disease management; host-pathogen interactions; immunologic memory; periodontitis.