IADR Abstract Archives
Different Effects of TLR2 and TLR4 Agonists on the Expression of Indolamin-2,3-Dioxygenase-1 in Human Periodontal Ligament Progenitor Cells
Objectives: Periodontal ligament progenitor cells are known to have significant immunomodulatory properties. Immunomodulatory effects of stem cells are largely mediated by indolamin-2,3-Dioxygenase 1 (IDO-1). The expression of IDO-1 is usually low in resting progenitor cells and might be activated by stimulation with pro-inflammatory mediators such as interferon (IFN)-γ or tumor necrosis factor-a. However, the effect of the toll-like receptor (TLR) signaling on the expression of IDO-1 is investigated rather poorly. In the present study, we investigated the effect of TLR2/1 agonist Pam3CSK4 and TLR4 agonist E. coli LPS on the basal and IFN-γ induced expression of IDO-1 in primary periodontal ligament progenitor cells.
Methods: Primary periodontal ligament progenitor cells were stimulated with either TLR2 agonist Pam3CSK4 (1 µg/ml) or TLR4 agonist E. coli LPS (1 µg/ml) in combination with soluble CD14 in the presence or in the absence of human recombinant IFN-γ (10 ng/ml). After 48 h of stimulation, the expression of IDO-1 in cells was measured by qPCR on gene level and by intracellular staining with PE-conjugated anti-IDO-1 antibody and following flow cytometry analysis on protein level. The protein expression of IDO-1 was quantified based on the measurements of fluorescence intensity.
Results: After 48 h stimulation both Pam3CSK4 and E. coli LPS induced a significant increase in gene-expression level of IDO-1 but have no significant influence on the protein expression. Stimulation of periodontal ligament progenitor cells with IFN-γ resulted in a significant increase of IDO-expression on both gene and protein levels. TLR4 agonist E. coli LPS had no significant effect on the IFN-γ induced IDO-1 expression. In contrast, TLR2 agonist significantly enhanced IFN-γ induced IDO-1 gene and protein expression in synergistic manner.
Conclusions: Our data indicate that TLR2 but not TLR4 signaling might significantly influence the expression of IDO-1 in periodontal ligament cells and potentially affect their immunomodulatory properties.
Methods: Primary periodontal ligament progenitor cells were stimulated with either TLR2 agonist Pam3CSK4 (1 µg/ml) or TLR4 agonist E. coli LPS (1 µg/ml) in combination with soluble CD14 in the presence or in the absence of human recombinant IFN-γ (10 ng/ml). After 48 h of stimulation, the expression of IDO-1 in cells was measured by qPCR on gene level and by intracellular staining with PE-conjugated anti-IDO-1 antibody and following flow cytometry analysis on protein level. The protein expression of IDO-1 was quantified based on the measurements of fluorescence intensity.
Results: After 48 h stimulation both Pam3CSK4 and E. coli LPS induced a significant increase in gene-expression level of IDO-1 but have no significant influence on the protein expression. Stimulation of periodontal ligament progenitor cells with IFN-γ resulted in a significant increase of IDO-expression on both gene and protein levels. TLR4 agonist E. coli LPS had no significant effect on the IFN-γ induced IDO-1 expression. In contrast, TLR2 agonist significantly enhanced IFN-γ induced IDO-1 gene and protein expression in synergistic manner.
Conclusions: Our data indicate that TLR2 but not TLR4 signaling might significantly influence the expression of IDO-1 in periodontal ligament cells and potentially affect their immunomodulatory properties.