부산대학교 도서관

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic human pathogen that can cause severe respiratory tract infections in patients suffered with cystic fibrosis (CF) or chronic obstructive pulmonary disease (COPD). Inflammatory responses against bacterial infection are initiated by the production of a variety of proinflammatory cytokines including Interleukin-1β (IL-1β). The expression of IL-1β was found to be upregulated in CF or COPD patients by the infection of P. aeruginosa, resulting in lung damage. The dried roots of Sophora flavescens (S. flavescens) have been widely used in traditional medicine for the treatment of inflammation and gastrointestinal hemorrhage. However, anti-inflammatory effect of S. flavescens has not been studied against P. aeruginosa-mediated inflammation. In this study, we investigated the anti-inflammatory mechanisms of S. flavescens by examining IL-1β expression induced by P. aeruginosa infection. S. flavescens inhibited the expression of Il-1β at the mRNA level in not only lung epithelial but also macrophage cells, and the protein expression level was further confirmed by ELISA analysis. The anti-inflammatory effect of S. flavescens was also effective on Staphylococcus aureus and PMA-mediated induction of IL-1β. These anti-inflammatory effects were found to be mediated by suppressing NF-κB activity via inhibiting IKKα/β phosphorylation followed by IκBα degradation. Furthermore, the protein expression level of caspase-1 required for the proteolytic processing of pro-IL-1β to mature IL-1β was diminished by S. flavescens. Taken together, this study demonstrates that S. flavescens has anti-inflammatory effects by suppressing IL-1β production under the control of NF-kappaB/ inflammasome signaling pathways.