Response of Cultured Primary Human Gingival and Periodontal Ligament Cells to Angiotensin II and IL1β Challenges

Angiotensin II (Ang II) plays a role in several inflammatory diseases and is capable of inducing the release of inflammatory mediators in several cell types. The objective was to investigate the potential of Ang II to induce mRNA expression of inflammatory mediators by cultured primary human periodontal cells. A synergistic effect of a co-treatment with Ang II and IL1β on mRNA expression of inflammatory mediators was also explored. Primary cultures of human fibroblast-like cells isolated from gingival and periodontal ligament tissues from 3 subjects were established using explant techniques. Immunophenotyping of STRO-1, AT1 and AT2 receptors was performed by flow cytometry analysis. Cell cultures were challenged with Ang II (1M) for 3, 6 and 24h with or without a co-treatment with IL1β (0.1ng/mL) for 24h. mRNA expression of inflammatory mediators was performed by real time quantitative polymerase chain reaction (RT-qPCR). We present, for the first time, a precise quantification for AT1 and AT2 receptors on human gingival and periodontal fibroblast-like cell types; the percentage of positive immunostaining compared to the total population of cells varied from 3.35% through 5.29% for AT1 and 2.97% through 4.57% for AT2. Ang II slightly upregulated mRNA expression of IL6 and CCL2/MCP1 in gingival cells and IL8 and PTGS2/COX2 in periodontal ligament cells. IL1β induced upregulation of IL8, IL6 CCL2/MCP1, PTGS2/COX2 and IL1β mRNA in both cell types. Co-treatment with Ang II and IL1β did not show a synergistic effect under these experimental conditions. Ang II shows a low potential to induce mRNA upregulation of inflammatory mediators in cultured primary human gingival and periodontal ligament cells, most likely due to the low percentage of Ang II receptors in such cells, and no synergistic effect with the co-treatment with IL1β.