Staphylococcus aureus strains cause the majority of pneumonia cases and are resistant to various antibiotics. Given this background, it is very important to discover novel host-targeted therapies. Licochalcone A (LAA), a natural plant product, has various biological activities, but its primary targets in S. aureus pneumonia remain unclear. Therefore, the purpose of this study was to identify its molecular target against S. aureus pneumonia. Network pharmacology analysis, histological assessment, enzyme-linked immunosorbent assays, and Western blotting were used to confirm the pharmacological effects. Network pharmacology revealed 33 potential targets of LAA and S. aureus pneumonia. Enrichment analysis revealed that these potential genes were enriched in the Toll-like receptor and NOD-like receptor signaling pathways. The results were further verified by experiments in which LAA alleviated histopathological changes, inflammatory infiltrating cells and inflammatory cytokines (TNF, IL-6, and IL-1β) in the serum and bronchoalveolar lavage fluid in vivo. Moreover, LAA treatment effectively reduced the expression levels of NF-κB, p-JNK, p-p38, NLRP3, ASC, caspase 1, IL-1β, and IL-18 in lung tissue. The in vitro experimental results were consistent with the in vivo results. Thus, our findings demonstrated that LAA exerts anti-infective effects on S. aureus-induced lung injury via suppression of the Toll-like receptor and NOD-like receptor signaling pathways, which provides a theoretical basis for understanding the function of LAA against S. aureus pneumonia and implies its potential clinical application.

To study the inhibitory activity of sodium houttuyfonate on biofilm of Staphylococcus aureus( S. aureus),a microdilution method was used measure the minimum inhibitory concentration( MIC) and the minimum bactericidal concentration( MBC) against S. aureus ATCC 25923and clinical isolates UAMS-1 in suspension. An agar plate method was used to determine the minimum biofilm inhibitory concentration( MBIC) and minimum biofilm bactericidal concentration( MBBC). The ability of sodium houttuyfonate which eliminated the biofilm was determined using confocal laser scanning microscopy,and the effect of sodium houttuyfonate on the secretion of S. aureus virulence factors was also determined using Western blot analysis. The results showed that sodium houttuyfonate had inhibitory activity against S. aureus in suspension with MIC and MBC values ranging from 16 to 64 μg /mL,and it had no obvious inhibitory effect on the mature biofilms with MBIC and MBBC values larger than 1 024 μg /mL. The sub-inhibitory concentration of sodium houttuyfonate had an inhibitory effect on the early stages of biofilm formation,which could significantly inhibit the secretion of α-haemolysin,enterotoxin A and B in dose-dependent manner. The results indicate that sodium houttuyfonate has good inhibitory activity against S. aureus in suspension and the early stages of biofilm formation.

为了研究柴胡皂甙D能否诱导HeLa细胞发生自噬,并初步探讨其机制,试验采用激光共聚焦显微镜、免疫印记等技术评价经柴胡皂甙D处理后的HeLa细胞的自噬水平.结果表明:经柴胡皂甙D处理后,激光共聚焦显微镜观察到GFP-LC3斑点显著增加;柴胡皂甙D能显著增加LC3-Ⅱ的表达;但自噬关键蛋白mTOR没有变化.说明柴胡皂甙D能诱导HeLa细胞发生自噬,并通过非mTOR依赖途径.

Phenol-soluble modulin(PSM) is a newly identified secreted virulence factor of Staphylococcus aureus.To study the effect of the subunits of PSM-α,the genes of PSM-α1,PSM-α2,PSM-α3 and PSM-α4 were cloned and the recombinant plasmid pGEX-PSM-α was constructed for expression in E.coli.The highly expressed soluble protein were purified and digested with thrombin to remove the GST-tag.Compared with negative control,the expression of human neutrophils IL-8 was increased significantly after co-culture with the purified PSM-α detected by ELISA kit.The current study demonstrated that PSM-α was able to cause disease by stimulating human neutrophils to release inflammatory factor.