DHA And EPA Suppress The Inflammatory Responses Of HGFs

Objectives: Porphyromonas gingivalis (P. gingivalis) is considered as the most important pathogen of chronic periodontitis, and its critical virulent factor is lipopolysaccharide (LPS). Human gingival fibroblasts (HGFs) are the major constituents of gingival tissues. Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are two major members of n-3 polyunsaturated fatty acids (PUFAs). The aim of this study was to investigate the in vitro effects of DHA and EPA on the production of pro-inflammatory mediators in HGFs induced by P. gingivalis LPS and heat-killed P. gingivalis.
Methods: HGFs were pretreated with DHA and EPA before stimulated by P. gingivalis LPS and heat-killed P. gingivalis. Then real-time PCR and enzyme linked immunosorbent assay (ELISA) were performed to detect the gene and protein expression of interleukin-6 (IL-6), IL-8 and IL-1β, respectively. To observe the possible mechanisms, real-time PCR and western blot were used to investigate the effects of DHA and EPA on the gene and protein expression of heme oxygenase-1 (HO-1), respectively.
Results: Pretreatment with DHA and EPA could significantly downregulate the gene expression of IL-6 and IL-1β, and downregulate the protein expression of IL-6 induced by P. gingivalis LPS and heat-killed P. gingivalis (p＜0.05), in a dose-dependent manner. The gene and protein expression of IL-8 was also decreased by DHA (p＜0.05). Futhermore, DHA and EPA could induce dose-dependent increase of the gene (p＜0.05) and protein expression of HO-1.
Conclusions: In conclusion, DHA and EPA possess anti-inflammatory activities against P. gingivalis LPS and heat-killed P. gingivalis induced inflammation in HGFs, which suggest that DHA and EPA may be useful in the prevention and/or treatment of periodontal diseases.