Liushen Wan alleviates the virulence and inflammation of Staphylococcus aureus via NLRP3 inflammasome and TLR2-NF-κB/p38 MAPK signaling pathways

Infectious diseases have been a major threat to health worldwide, with bacterial infections being particularly prominent. Staphylococcus aureus (S. aureus) infections are associated with the most deaths. Inhibition of virulence factor and excessive inflammation induced by S. aureus has become a potential antibiotic alternative/synergistic therapy without causing greater survival pressure to prevent the emergence of "superbugs" in the future. Liushen Wan (LSW), a traditional Chinese medicine, used for multiple bacterial infectious diseases. In this work, we researched its therapeutic effect and explored the potential mechanism of LSW aiming at S. aureus in vivo and in vitro. Minimal inhibitory concentration (MIC) assay, hemolysis assay, invasion assay, staphyloxanthin assay and evolution of resistance assay were performed to show that LSW alleviated the virulence of S. aureus without suppressing S. aureus activity, and short-term use of LSW did not make bacteria resistant to it. Biofilm inhibition assay demonstrated that LSW inhibited the formation of biofilm and destroyed mature biofilm of S. aureus. In vitro experiments using RT-qPCR, ELISA and western blot analysis indicated LSW inhibited the inflammatory reaction triggered by HK-S. aureus and S. aureus through NLRP3 inflammasome and TLR2-NF-κB/p38 MAPK pathway. Moreover, LSW alleviated lung damage induced by S. aureus. Taken together, LSW is a promising antibacterial, anti-virulence and anti-inflammatory drug, which could provide the pharmacological basis on the traditional application of LSW for diseases associated with S. aureus infection in clinical.