Chlorogenic Acid as a Positive Regulator in LPS-PG-Induced Inflammation via TLR4/MyD88-Mediated NF-κB and PI3K/MAPK Signaling Cascades in Human Gingival Fibroblasts

Figure 1

Attenuated production of NO and PGE₂ as well as protein expression levels of their responsible enzymes, iNOS, and COX-2, by CGA treatment in LPS-PG-stimulated HGF-1 cells. Cells were preincubated with or without the indicated concentrations of CGA for 2 h, then incubated with LPS-PG (1 μg/mL) for 18 h at 37°C in a humidified atmosphere containing 5% CO₂. Griess reaction, ELISA, and western blot analysis were applied to measure the concentration of inflammatory mediators and protein expression levels. CGA treatment significantly inhibited LPS-PG-stimulated NO (a) and PGE₂ production (b) as well as protein expression of iNOS and COX-2 (c) in HGF-1 cells. In addition, the cell viability was evaluated by MTS assay, and CGA treatment did not give any cytotoxic effect in HGF-1 cells (d). The relative protein expression of each target was measured by densitometry and normalized to the protein levels of actin, an internal control. Data represent the of triplicate experiments. ^# vs. NC group; and vs. LPS-PG group. Negative control (NC) group refers that CGA and LPS-PG were not treated. CGA: chlorogenic acid; COX-2: cyclooxygenase-2; HGF: human gingival fibroblast; iNOS: inducible nitric oxide synthase; LPS-PG: lipopolysaccharide from P. gingivalis; PGE₂: prostaglandin E₂.

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