Background: C5a receptor antagonist PMX205 is a synthetic hexapeptide capable of blocking C5a-C5a receptor (C5aR) axis by simulating C5a active C-terminal amino acid residues. This hexapeptide presents good anti-inflammatory effects in a series of inflammation models. The anti-inflammatory effect of PMX205 on periodontitis is yet to be fully fathomed.
Objective: To examine the anti-inflammatory effects of PMX205 on RAW264.7 mouse macrophages exposed to gingipain extracts and Porphyromonas gingivalis (P. gingivalis).
Methods: MTT assay was carried out so as to specify the cytotoxicity of PMX205. RAW264.7 cells were co-cultured in vitro with gingipain extracts or P. gingivalis to simulate the periodontitis inflammatory milieu. Real-time quantitative PCR, ELISA and Griess assay were performed in order to detect tumor necrosis factor-α (TNF-α), IL-6, IL-23, nitric oxide (NO), IL-10, transforming growth factor-β1 (TGF-β1), andarginase-1 (Arg-1). Furthermore, phagocytosis assay was done to evaluate the phagocytic capacity of RAW 264.7 cells. Finally, western blot analysis was conducted to evaluate myeloid differentiation factor 88 (MyD88).
Results: PMX205 increased the expression levels of bacteriostatic substances (NO and IL-23) and anti-inflammatory cytokines (TGF-β1, IL-10 and Arg-1); however, it reduced the expression levels of proinflammatory cytokines TNF-α and IL-6 once RAW 264.7 macrophages were stimulated via gingipain extracts or P. gingivalis. In addition, PMX205 promoted the macrophage phagocytosis and down-regulated protein expression of MyD88.
Conclusion: PMX205 has recognizable anti-inflammatory effects in RAW 264.7 cell inflammation model, a finding which probably opens doors to future investigations on new targets for the prevention and treatment of chronic periodontitis.