Title: 1438 - PGRP1 Inhibits TNF-α-mediated Effects on PDL Cells
Aaron Compton (Presenter)
Oregon Health & Science University
Li-Jung Lin, Oregon Health & Science University
Sivaraman Prakasam, Oregon Health & Science University
Objectives: Periodontitis is an oral infectious inflammatory disease that is characterized by the destruction of the periodontal ligament (PDL) and alveolar bone. Bacterial products in the gingival sulcus upregulate TNF-α expression in periodontal tissue. TNF-α, an inflammatory cytokine, induces apoptosis of PDL cells and alveolar bone. Previous studies have shown the ability of peptidoglycan recognition protein-1 (PGRP1, a soluble host immune mediator, to inhibit the TNF-α-mediated apoptosis of tumor cells. Our objective was to determine whether PGRP1 can inhibit TNF-α mediated effects on PDL cells.
Methods: Cultured Immortalized mouse PDL cells (SV11) were stimulated/conditioned as follow: 1) TNF-α (10ng/mL), 2) PGRP1 (10nM/ml), or 3) TNF-α (10ng/mL) with PGRP1 (10nM/ml), along with appropriate positive and negative controls for 6, 12, and 24 hours. Cells were then harvested and analyzed for apoptosis & cell death through flow cytometry. Culture supernatants were analyzed through ELISA for expression of MMP13. Cells were also lysed and analyzed by western blot for pMLKL to determine occurrence of necroptosis. All experiments were done 3 times and with 3 replicates. Means and Standard deviations were calculated for different treatments. Paired T tests were used to compare the means at a significance level of p ≤ 0.05.
Results: SV11 cells undergo significantly increased apoptosis at 12 hours with TNF-α treatment compared to no treatment. This was significantly attenuated with PGRP1, similar to a specific inhibitor of TNF-α. There were no differences in apoptosis at 6 hours. MMP13 was significantly upregulated with TNF-α treatment. This upregulation was inhibited by both PGRP1 as well as TNF-α inhibitor. Phosphorylated MLKL proteins were not detected with any of the treatments.
Conclusions: PGRP1 may protect against TNF-α-mediated inflammation and apoptosis. Thus, PGRP1 may play a role in maintaining tissue homeostasis during periodontal health. Additionally, in the near future, culture supernatants will be analyzed for MMP-3, IL6, and IL8 expression.
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE