Taiwanese green propolis suppresses NLRP3 inflammasome activation and induces Nrf2/HO-1 pathway to reduce periodontal pathogen-induced endothelial inflammation

Objective: Periodontitis is a chronic inflammatory disease associated with systemic conditions, including cardiovascular diseases. Porphyromonas gingivalis (Pg), a key periodontal pathogen, contributes to vascular endothelial dysfunction through its virulence factors. This study aimed to investigate the protective effects of Taiwanese green propolis (TGP) against Pg-derived lipopolysaccharide (Pg-LPS)-induced endothelial inflammation, focusing on its modulation of the NLRP3 inflammasome and Nrf2/HO-1 signaling pathways.

Design: Human aortic endothelial cells (HAECs) were stimulated with Pg-LPS in the presence or absence of TGP. The expression of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) was assessed using Real-Time PCR and ELISA. ROS production was evaluated using fluorescence-based assays, while NF-κB activation and Nrf2 transcriptional activity were analyzed via luciferase reporter assays. Pharmacological inhibitors were used to confirm the involvement of these pathways.

Results: TGP significantly reduced Pg-LPS-induced IL-1β, TNF-α, and IL-6 expression in HAECs. It inhibited NF-κB activation, suppressed ROS generation, and attenuated NLRP3 inflammasome activation. Additionally, TGP upregulated HO-1 expression and enhanced Nrf2 transcriptional activity, as evidenced by ARE-driven luciferase reporter assays. Pharmacological inhibition of Nrf2 and HO-1 reversed TGP's anti-inflammatory effects, confirming that the Nrf2/HO-1 axis is critical for its protective function.

Conclusions: These findings demonstrate that TGP exerts anti-inflammatory and cytoprotective effects by suppressing NLRP3 inflammasome activation and enhancing the Nrf2/HO-1 pathway, reducing Pg-LPS-induced endothelial inflammation. This study suggests that TGP could be a promising natural therapeutic agent for mitigating periodontal pathogen-induced systemic inflammation.

Inflammation; NLRP3 inflammasome; Oxidative stress; Porphyromonas gingivalis; Taiwanese green propolis.