IADR Abstract Archives
Porphyromonas gingivalis Induced PD-L1 (B7-H1) Up-regulation and Signaling in Oral Epithelial Cells
Objectives:
The immune-regulatory programmed death-ligand 1 (PD-L1) receptor is a co-signaling molecule in the cell-mediated immune response. PD-L1 (B7-H1) mediates regulation of T cell activation and tolerance and down-regulates T cell function and survival. Overexpression of PD-L1 on host cells may contribute to chronicity of inflammation, while tumor-associated PD-L1 expression has been linked with mechanisms by which tumor cells evade immune surveillance. Porphyromonas gingivalis (P. gingivalis), a keystone pathogen in periodontitis, invades host cells and expresses several virulence factors. The aim of this study was to investigate the signalling pathway of the PD-L1 induction in epithelial cells by membrane fraction of P. gingivalis.
Methods:
Human squamous carcinoma cells and primary gingival keratinocytes were stimulated with isolated P. gingivalis membrane fractions and LPS. Chemical inhibitors were used to identify possible members of the signaling pathway mediating the PD-L1 up-regulation. CRISPR/Cas9 method was applied to generate Myd88 knock-out cells. PD-L1 protein expression was quantified by Western blot analysis.
Results: Up-regulation of PD-L1 induced by P. gingivalis membrane could be blocked effectively using getifinib, an inhibitor of the receptor-interacting serine/threonine-protein kinase 2 (RIPK2), a component of the signaling cascades of innate and adaptive immune response that is recruited by NOD1 and NOD2 after activation and oligomerization. RIPK2 could mediate up-regulation of PD-L1 through activation of nuclear factor kappa B (NfκB). The NFκB inhibitor BAY11 – 7082 (2.5 µM) reduced the expression by 64.4± 23%, gefitinib caused a reduction of PD-L1 expression by 57.6± 22% (2.5µM) and 75.1± 23% (10µM). Knock-out of MyD88 and LPS stimulation demonstrated that PD-L1 up-regulation was MyD88-independent.
Conclusions:
We provide evidence that membrane proteins of P. gingivalis up-regulate the immune-regulatory receptor PD-L1 using a pathway that includes a component of the NOD1 and NOD2 signaling cascade. The influence of bacterial proteins on the PD-L1 pathway may contribute to chronification of P. gingivalis related infections.
The immune-regulatory programmed death-ligand 1 (PD-L1) receptor is a co-signaling molecule in the cell-mediated immune response. PD-L1 (B7-H1) mediates regulation of T cell activation and tolerance and down-regulates T cell function and survival. Overexpression of PD-L1 on host cells may contribute to chronicity of inflammation, while tumor-associated PD-L1 expression has been linked with mechanisms by which tumor cells evade immune surveillance. Porphyromonas gingivalis (P. gingivalis), a keystone pathogen in periodontitis, invades host cells and expresses several virulence factors. The aim of this study was to investigate the signalling pathway of the PD-L1 induction in epithelial cells by membrane fraction of P. gingivalis.
Methods:
Human squamous carcinoma cells and primary gingival keratinocytes were stimulated with isolated P. gingivalis membrane fractions and LPS. Chemical inhibitors were used to identify possible members of the signaling pathway mediating the PD-L1 up-regulation. CRISPR/Cas9 method was applied to generate Myd88 knock-out cells. PD-L1 protein expression was quantified by Western blot analysis.
Results: Up-regulation of PD-L1 induced by P. gingivalis membrane could be blocked effectively using getifinib, an inhibitor of the receptor-interacting serine/threonine-protein kinase 2 (RIPK2), a component of the signaling cascades of innate and adaptive immune response that is recruited by NOD1 and NOD2 after activation and oligomerization. RIPK2 could mediate up-regulation of PD-L1 through activation of nuclear factor kappa B (NfκB). The NFκB inhibitor BAY11 – 7082 (2.5 µM) reduced the expression by 64.4± 23%, gefitinib caused a reduction of PD-L1 expression by 57.6± 22% (2.5µM) and 75.1± 23% (10µM). Knock-out of MyD88 and LPS stimulation demonstrated that PD-L1 up-regulation was MyD88-independent.
Conclusions:
We provide evidence that membrane proteins of P. gingivalis up-regulate the immune-regulatory receptor PD-L1 using a pathway that includes a component of the NOD1 and NOD2 signaling cascade. The influence of bacterial proteins on the PD-L1 pathway may contribute to chronification of P. gingivalis related infections.