Concentration of human PGE2 was measured by an ELISA kit (R&D Systems) according to the manufacturer’s protocol. Cells (1 × 105 cells/well) were cultured in complete medium in wells of a 6-well plate. After being washed with PBS, the cells were exposed to serum-free medium containing LPS (1 μg/ml) and/or EETC (10 mg/ml) for 24 h. The culture medium was collected by centrifugation at 1,500 rpm for 10 min and was examined by ELISA. DPB#1, DPB#2, and DPB#3 were independently co-cultured with RAW264.7 macrophages, IHOK keratinocytes, IGF gingival fibroblasts, YD38 gingival epithelial cells. Cultured media were harvested by centrifugation and used to determine the level of PGE2. LPS extracted from the three DPB samples (DPB#1-LPS, DPB#2-LPS, and DPB#3-LPS) were also treated instead of DPB.