Antagonistic effect of Polygonum cillinerve against methicillin-resistant Staphylococcus aureus and its immunoregulatory mechanism：An experimental study

Abstract:

Objective：To investigate whether Polygonum cillinerve can antagonize methicillin-resistant Staphylococcus aureus（MRSA） using a multilevel evaluation system and the immunoregulatory mechanism of its antagonistic effect. Methods：Tube double dilution was used to perform drug sensitivity test to observe the inhibitory effect of Polygonum cillinerve on the growth of Staphylococcus aureus and whether Polygonum cillinerve can affect the invasion of MRSA in host cells. Fibronectin adhesion test was used to evaluate the in－fluence of Polygonum cillinerve on bacterial adhesion. Real-time PCR was used to analyze the effect of Polygonum cillinerve on the mRNA expression of Toll-like receptors（TLRs），nucleotide-binding oligomerization domains（NODs），and downstream inflammatory factors tumor necrosis factor-α（TNF-α） and interleukin-6（IL-6） in AT-Ⅱ cells. Western blot was used to investigate the effect of Polygonum cillinerve on the protein expression of mitogen-activated protein kinase（MAPK） and nuclear factor-κB（NF-κB） in AT-Ⅱ cells. Results：The Polygonum cillinerve group had a significantly lower number of AT-Ⅱ cells with MRSA invasion than the model group and the positive control group（471.57±34.32 vs. 1 014.54±127.51/810.05±101.33，P<0.05），as well as a significant－ly lower fibronectin adsorption ratio in AT-Ⅱ cells infected with MRSA（0.25±0.01 vs. 1.04±0.12/0.74±0.07，P<0.05）. Real-time PCR showed that MRSA significantly increased the levels of TLR2，NOD2，and downstream inflammatory factors TNF-α and IL-6（P<0.05），while Polygonum cillinerve significantly reduced their levels（P<0.05）. Western blot showed that Polygonum cillinerve sig－nificantly downregulated the expression of the proteins involved in the MAPK and NF-κB signaling pathways（P<0.05）. Conclusion：Polygonum cillinerve can antagonize MRSA，and the MAPK and NF-κB signaling pathways might be involved in this process. It fur－ther regulates the pattern recognition receptors TLRs/NOD-like receptors and the downstream inflammatory factors TNF-α and IL-6.