Programmed death 1 (PD-1) and PD-1 ligand (PD-L1) expression in chronic apical periodontitis

Abstract

This study aimed to examine programmed death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) expression on leukocytes from chronic apical periodontitis, and to determine the levels of cytokines in the apical periodontitis lesions. Methods: Leukocytes from healthy gingival tissue (n=16) and chronic apical periodontitis (n=10) were evaluated using flow cytometry. The PD-1 and PDL-1 expressions were evaluated using flow cytometry. The cytokine levels were evaluated by enzyme-linked immunosorbent assay. Data were analyzed using one-way ANOVA. The statistical significance level was set at P<0.05. Results: Results showed that the apical periodontitis lesions are more infiltrated by PD-1 + and PDL1 + lymphocytes than the control samples. In addition, the PDL-1 expression was detected on macrophages in the apical periodontitis lesions, and was significantly higher compared to leukocytes from healthy gingival tissue. The IFN-γ, TGF-β, IL-10, and TNF-α levels were significantly higher in the apical periodontitis lesions compared to control samples. Conclusion: The PD-1, PD-L1, and CTLA-4 molecules are evident in apical periodontitis, and can be an important immune checkpoint in chronic periapical periodontitis.

Mechanisms of bone remodeling and therapeutic strategies in chronic apical periodontitis

“…The development of exacerbated inflammation in AP is likely to be distinctly influenced by the macrophage migration inhibitory factors -794 CATT5-8 and -173G>C (Freer-Rojas et al, 2020). One study showed that the expression of PD-L1 was more significant in macrophages at the focal site of CAP than in the control group (Delgado et al, 2019). PD-L1 binds to PD-1 on T cells to inhibit immune function, which may be related to the persistence of bacteria in CAP and chronic pulp infection.…”

PD-L1, a Potential Immunomodulator Linking Immunology and Orthodontically Induced Inflammatory Root Resorption (OIIRR): Friend or Foe?

“…Both PD-1 and PD-L1 levels were found to be significantly enhanced in CD4 + and CD8 + T lymphocytes from periodontitis patients compared with healthy individuals [ 80 ]. Recently, it was also reported that apical periodontitis lesions show more PD-1 positive and PD-L1 positive lymphocyte infiltrations in conjunction with higher cytokine levels [ 81 ]. Moreover, it is of importance that mesenchymal stem cells taken from dental pulp and PDL show an increase in PD-L1 and exhibit immunoregulatory properties [ 82 ].…”